C3-binding agents and methods of use thereof

ABSTRACT

The present disclosure provides binding agents, such as antibodies (including single chain variable fragments), that specifically bind complement component C3, including human C3, compositions comprising same, and methods of their use. The disclosure also provides related polynucleotides and vectors encoding the binding agents and cells comprising same.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a divisional and claims priority to pending U.S. patent application Ser. No. 17/406,991, filed Aug. 19, 2021, which is a divisional and claims priority to U.S. patent application Ser. No. 16/371,684, filed Apr. 1, 2019, issued as U.S. Pat. No. 11,136,381, which claims the priority benefit of U.S. Provisional Application No. 62/652,253, filed Apr. 3, 2018. The contents of the prior applications are incorporated herein by reference in their entirety.

SEQUENCE LISTING

This application contains a Sequence Listing that has been submitted electronically as an XML file named 47702-0011003_SL_ST26.xml. The XML file, created on Jul. 28, 2023, is 221,274 bytes in size. The material in the XML file is hereby incorporated by reference in its entirety.

FIELD OF THE INVENTION

The present disclosure generally relates to agents that bind complement component C3 (C3), particularly antibodies that bind human C3, as well as therapeutic methods of using the agents.

BACKGROUND

The complement cascade is primarily involved in the detection and removal of foreign pathogens such as bacteria. The complement system includes more than 30 cell-associated and circulating proteins (e.g., C1, C1q, C1r, C1s, C2, C3, C3a, C3b, C4, Factor B, Factor D, Factor H, Factor I). There are three main pathways that activate complement, the classical pathway (CP), the lectin pathway (MBL), and the alternative pathway (AP).

The three complement pathways are initiated by different factors, each resulting in the cleavage of complement component C3. The classical complement pathway is activated when the C1 complex binds specific antigen-antibody complexes, often immunoglobulin M (IgM), IgG3, or IgG1. This induces a conformational change in the C1 complex, allowing it to cleave C4 and C2 to generate the C4bC2b complex. C4bC2b acts as the C3 convertase of the classical pathway. The lectin complement pathway is activated when mannose-binding lectin (MBL) binds mannose-containing polysaccharides on microorganisms, initiating the cleavage of C4 and C2 by the MBL-MBL-associated serine protease complex. As in the classical pathway, the C4bC2b complex forms the C3 convertase of the lectin pathway. The oldest evolutionary signaling pathway of the three, the alternative complement pathway acts both independently of, and as an amplification loop for, the classical and lectin pathways. The alternative complement pathway undergoes low-level self-activation through the slow, spontaneous hydrolysis of C3. Once hydrolyzed, C3(H₂O) binds complement Factor B, which is subsequently cleaved by complement Factor D into C3(H₂O)Bb, forming the C3 convertase of the alternative complement pathway. These different pathways converge with the cleavage of complement component C3 into C3a and C3b. On host cells, endogenous factors shut down the complement cascade. On pathogens, the complement cascade continues with the cleavage of complement component C5, which triggers cell death via phagocytosis, inflammation, and ultimately membrane attack complex (MAC) activation. (Immunobiology: The Immune System in Health and Disease. 5th edition; Chapter: The complement system and innate immunity; New York: Garland Science; 2001.)

Although the complement system is traditionally considered part of the immune system, i.e., protection against foreign pathogens, complement activity also has a role in maintaining healthy tissue. For example, clearance of apoptotic cells is facilitated by the complement pathway. However, inappropriate or excessive complement activation is thought to be a cause or contributing factor to a number of diseases and disorders.

Among the diseases that complement activation is thought to be involved in is aged-related macular degeneration (AMD). AMD is the main cause of vision loss among the elderly in developed countries and globally affects approximately 9% of the world's population. There are two types of AMD, dry (approximately 85-90% of patients) and wet (approximately 10-15% of patients). Wet AMD occurs when abnormal blood vessels (known as choroidal neovascularization or CNV) grow under the retina and macula. These new blood vessels may bleed and leak fluid, causing the macula to bulge or lift up from its normally flat position, thus distorting or destroying central vision. Under these circumstances, vision loss may be rapid and severe. Dry AMD is characterized by formation of drusen under the retina. Geographic atrophy (GA) is the advanced (late) form of dry AMD. GA is characterized by the progressive loss of areas of the retinal pigment epithelium (RPE), loss of photoreceptors (rods and cones), loss of neuroretina, and loss of choriocapillaris. The loss of one or more of these cells and/or tissues results in permanent central vision loss. Although there has been some progress in the development of new therapeutics for wet AMD, particularly the use of VEGF inhibitors, there are no approved treatments for dry AMD and/or GA. Thus, new therapeutic agents and methods of using those agents for treatment of AMD are needed.

BRIEF SUMMARY

The present disclosure provides agents that bind complement component C3 (e.g., SEQ ID NO:1). The agents include, but are not limited to, polypeptides such as antibodies that specifically bind C3. The agents may be referred to herein as “C3-binding agents”. The disclosure provides methods of making and of using a C3-binding agent. In some embodiments, a C3-binding agent inhibits C3 activity. In some embodiments, a C3-binding agent inhibits complement activation. In some embodiments, a C3-binding agent inhibits activation of the classical complement pathway, the alternative complement pathway, or both the classical and alternative complement pathways. In some embodiments, a C3-binding agent is used in a combination therapy. In some embodiments, a C3-binding agent is used in combination with at least one additional therapeutic agent.

The disclosure also provides compositions comprising the C3-binding agents described herein. In some embodiments, the disclosure provides pharmaceutical compositions comprising the C3-binding agents described herein. Polynucleotides and/or vectors encoding the C3-binding agents and methods of making the agents are also provided. Cells comprising or producing the C3-binding agents described herein are provided. Cells comprising the polynucleotides and/or the vectors described herein are also provided.

In one aspect, the present disclosure provides agents that bind C3 (e.g., SEQ ID NO:1). In some embodiments, an agent binds human C3 (e.g., SEQ ID NO:1). In some embodiments, an agent binds cynomolgus monkey (“cyno”) C3 (e.g., SEQ ID NO:32). In some embodiments, an agent binds human C3 and cyno C3. In some embodiments, an agent is an antibody. In some embodiments, an agent is an antibody that binds human C3. In some embodiments, an agent is an antibody that binds cyno C3. In some embodiments, an agent is an antibody that binds human C3 and cyno C3. In some embodiments, an agent is an antibody that binds human C3 and does not bind mouse C3. In some embodiments, the agent does not bind mouse C3 at a detectable level. In some embodiments, an agent is an antibody that binds human C3 and does not bind rat C3. In some embodiments, the agent does not bind rat C3 at a detectable level. In some embodiments, an agent is an antibody that binds human C3 and does not bind human C3b. In some embodiments, the agent does not bind human C3b at a detectable level. In some embodiments, an agent is an antibody that binds human C3 with an affinity that is at least 50-fold greater than the antibody's affinity for human C3b. In some embodiments, an agent is an antibody that binds human C3 with an affinity that is at least 100-fold greater than the antibody's affinity for human C3b. In some embodiments, the affinity is measured using surface plasmon resonance (SPR) technology in a Biacore system as described herein or as known to those of skill in the art.

In one aspect, the present disclosure provides an agent (e.g., an antibody) that specifically binds human C3 (e.g., SEQ ID NO:1) and has at least one or more (e.g., 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12) of the following properties: (a) binds to cyno C3 (e.g., SEQ ID NO:32), (b) inhibits C3 cleavage, (c) inhibits C3 cleavage and C3a release, (d) inhibits activation of the alternative complement pathway (e.g., as assessed by hemolytic assays), (e) inhibits activation of the classical complement pathway (e.g., as assessed by hemolytic assays), (f) inhibits activation of the alternative complement pathway and classical complement pathway (e.g., as assessed by hemolytic assays), (g) does not detectably bind to Factor Bb, (h) does not detectably bind to C3d, (i) does not detectably bind to C3a, (j) does not detectably bind to C3b, (k) does not detectably bind to iC3b, (l) does not detectably bind to Factor Bb and C3d, (m) does not detectably bind to Factor Bb, C3d, and C3a, (n) does not detectably bind to Factor Bb, C3d, C3a, C3b, and iC3b, (o) binds to human C3 (e.g., SEQ ID NO:1) with a greater affinity than compstatin, and (p) has a half-life of about 4-5 days in human vitreous humor. In certain embodiments, the C3-binding agent inhibits activation of the classical complement pathway (e.g., as assessed by hemolytic assays). In some embodiments, the C3-binding agent inhibits activation of the alternative complement pathway and classical complement pathway (e.g., as assessed by hemolytic assays). In certain embodiments, the C3-binding agent comprises: (a) a heavy chain CDR1 comprising SEQ ID NO:7, a heavy chain CDR2 comprising SEQ ID NO:8, a heavy chain CDR3 comprising SEQ ID NO:9, a light chain CDR1 comprising SEQ ID NO:10, a light chain CDR2 comprising SEQ ID NO:11, and a light chain CDR3 comprising SEQ ID NO:12; (b) a heavy chain CDR1 comprising SEQ ID NO:7, a heavy chain CDR2 comprising SEQ ID NO:13, a heavy chain CDR3 comprising SEQ ID NO:9, a light chain CDR1 comprising SEQ ID NO:10, a light chain CDR2 comprising SEQ ID NO:11, and a light chain CDR3 comprising SEQ ID NO:12; (c) a heavy chain CDR1 comprising SEQ ID NO:7, a heavy chain CDR2 comprising SEQ ID NO:14, a heavy chain CDR3 comprising SEQ ID NO:9, a light chain CDR1 comprising SEQ ID NO:10, a light chain CDR2 comprising SEQ ID NO:11, and a light chain CDR3 comprising SEQ ID NO:12; (d) a heavy chain CDR1 comprising SEQ ID NO:7, a heavy chain CDR2 comprising SEQ ID NO:15, a heavy chain CDR3 comprising SEQ ID NO:9, a light chain CDR1 comprising SEQ ID NO:10, a light chain CDR2 comprising SEQ ID NO:11, and a light chain CDR3 comprising SEQ ID NO:12; (e) a heavy chain CDR1 comprising SEQ ID NO:7, a heavy chain CDR2 comprising SEQ ID NO:16, a heavy chain CDR3 comprising SEQ ID NO:9, a light chain CDR1 comprising SEQ ID NO:10, a light chain CDR2 comprising SEQ ID NO:11, and a light chain CDR3 comprising SEQ ID NO:12; or (f) a heavy chain CDR1 comprising SEQ ID NO:7, a heavy chain CDR2 comprising SEQ ID NO:17, a heavy chain CDR3 comprising SEQ ID NO:9, a light chain CDR1 comprising SEQ ID NO:10, a light chain CDR2 comprising SEQ ID NO:11, and a light chain CDR3 comprising SEQ ID NO:12. In certain embodiments, the C3-binding agent comprises a heavy chain CDR1 comprising SEQ ID NO:7, a heavy chain CDR2 comprising SEQ ID NO:14, a heavy chain CDR3 comprising SEQ ID NO:9, a light chain CDR1 comprising SEQ ID NO:10, a light chain CDR2 comprising SEQ ID NO:11, and a light chain CDR3 comprising SEQ ID NO:12. In certain embodiments, the C3-binding agent comprises: (a) a heavy chain variable region comprising SEQ ID NO:20 and a light chain variable region comprising SEQ ID NO:25; (b) a heavy chain variable region comprising SEQ ID NO:21 and a light chain variable region comprising SEQ ID NO:25; (c) a heavy chain variable region comprising SEQ ID NO:22 and a light chain variable region comprising SEQ ID NO:25; (d) a heavy chain variable region comprising SEQ ID NO:23 and a light chain variable region comprising SEQ ID NO:25; or (e) a heavy chain variable region comprising SEQ ID NO:24 and a light chain variable region comprising SEQ ID NO:25. In certain embodiments, the C3-binding agent comprises a heavy chain variable region comprising SEQ ID NO:21 and a light chain variable region comprising SEQ ID NO:25.

In another aspect, the present disclosure provides an agent (e.g., an antibody) that specifically binds human C3 and has at least one or more (e.g., 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12) of the following properties: (a) binds to cyno C3 (e.g., SEQ ID NO:32), (b) inhibits C3 cleavage, (c) inhibits C3 cleavage and C3a release, (d) inhibits activation of the alternative complement pathway (e.g., as assessed by hemolytic assays), (e) inhibits activation of the classical complement pathway (e.g., as assessed by hemolytic assays), (f) inhibits activation of the alternative complement pathway and classical complement pathway (e.g., as assessed by hemolytic assays), (g) does not detectably bind to Factor Bb, (h) does not detectably bind to C3d, (i) does not detectably bind to C3a, (j) does not detectably bind to C3b, (k) does not detectably bind to iC3b, (l) does not detectably bind to Factor Bb and C3d, (m) does not detectably bind to Factor Bb, C3d, and C3a, (n) does not detectably bind to Factor Bb, C3d, C3a, C3b, and iC3b, (o) binds to human C3 (e.g., SEQ ID NO:1) with a greater affinity than compstatin, and (p) has a half-life of about 4-5 days in human vitreous humor, wherein the antibody or antigen-binding fragment is for use in the prophylaxis or treatment of a disease selected from AMD, macular degeneration, diabetic retinopathy, retinopathy of prematurity, macular dystrophy, retinal dystrophy, uveitis, keratitis, scleritis, retinitis pigmentosa, choroidal neovascularization, retinal neovascularization, and ocular inflammation. In certain embodiments, the disease is AMD. In certain embodiments, the agent (e.g., an antibody or antigen-binding fragment thereof) inhibits activation of the alternative complement pathway and classical complement pathway (e.g., as assessed by hemolytic assays).

In some embodiments, an agent (e.g., an antibody) that specifically binds C3 comprises: (a) a heavy chain CDR1 comprising GYTFTDFYMD (SEQ ID NO:7); a heavy chain CDR2 comprising YIYPHNGGTTYNQNFTG (SEQ ID NO:8), YIYPHNGGTTYNQQFTG (SEQ ID NO:13), YIYPHNAGTTYNQQFTG (SEQ ID NO:14), YIYPHNTGTTYNQQFTG (SEQ ID NO:15), YIYPHEGGTTYNQQFTG (SEQ ID NO:16), or YIYPHQGGTTYNQQFTG (SEQ ID NO:17), and a heavy chain CDR3 comprising RGGFDFDY (SEQ ID NO:9); and/or (b) a light chain CDR1 comprising KASENVDTYVS (SEQ ID NO:10); a light chain CDR2 comprising GASNRYT (SEQ ID NO:11); and a light chain CDR3 comprising GQSHSYPLT (SEQ ID NO:12). In some embodiments, an agent (e.g., an antibody) that specifically binds C3 comprises a heavy chain CDR1 comprising GYTFTDFYMD (SEQ ID NO:7); a heavy chain CDR2 comprising YIYPHNGGTTYNQNFTG (SEQ ID NO:8), YIYPHNGGTTYNQQFTG (SEQ ID NO:13), YIYPHNAGTTYNQQFTG (SEQ ID NO:14), YIYPHNTGTTYNQQFTG (SEQ ID NO:15), YIYPHEGGTTYNQQFTG (SEQ ID NO:16), or YIYPHQGGTTYNQQFTG (SEQ ID NO:17), and a heavy chain CDR3 comprising RGGFDFDY (SEQ ID NO:9). In some embodiments, an agent (e.g., an antibody) that specifically binds C3 comprises a light chain CDR1 comprising KASENVDTYVS (SEQ ID NO: 10); a light chain CDR2 comprising GASNRYT (SEQ ID NO:11); and a light chain CDR3 comprising GQSHSYPLT (SEQ ID NO:12). In some embodiments, an agent (e.g., an antibody) that specifically binds C3 comprises: (a) a heavy chain CDR1 comprising GYTFTDFYMD (SEQ ID NO:7); a heavy chain CDR2 comprising YIYPHNGGTTYNQNFTG (SEQ ID NO:8), and a heavy chain CDR3 comprising RGGFDFDY (SEQ ID NO:9); and (b) a light chain CDR1 comprising KASENVDTYVS (SEQ ID NO:10); a light chain CDR2 comprising GASNRYT (SEQ ID NO:11); and a light chain CDR3 comprising GQSHSYPLT (SEQ ID NO:12). In some embodiments, an agent (e.g., an antibody) that specifically binds C3 comprises: (a) a heavy chain CDR1 comprising GYTFTDFYMD (SEQ ID NO:7); a heavy chain CDR2 comprising YIYPHNGGTTYNQQFTG (SEQ ID NO:13), and a heavy chain CDR3 comprising RGGFDFDY (SEQ ID NO:9); and (b) a light chain CDR1 comprising KASENVDTYVS (SEQ ID NO:10); a light chain CDR2 comprising GASNRYT (SEQ ID NO:11); and a light chain CDR3 comprising GQSHSYPLT (SEQ ID NO: 12). In some embodiments, an agent (e.g., an antibody) that specifically binds C3 comprises: (a) a heavy chain CDR1 comprising GYTFTDFYMD (SEQ ID NO:7); a heavy chain CDR2 comprising YIYPHNAGTTYNQQFTG (SEQ ID NO:14), and a heavy chain CDR3 comprising RGGFDFDY (SEQ ID NO:9); and (b) a light chain CDR1 comprising KASENVDTYVS (SEQ ID NO:10); a light chain CDR2 comprising GASNRYT (SEQ ID NO:11); and a light chain CDR3 comprising GQSHSYPLT (SEQ ID NO:12). In some embodiments, an agent (e.g., an antibody) that specifically binds C3 comprises: (a) a heavy chain CDR1 comprising GYTFTDFYMD (SEQ ID NO:7); a heavy chain CDR2 comprising YIYPHNTGTTYNQQFTG (SEQ ID NO:15), and a heavy chain CDR3 comprising RGGFDFDY (SEQ ID NO:9); and (b) a light chain CDR1 comprising KASENVDTYVS (SEQ ID NO:10); a light chain CDR2 comprising GASNRYT (SEQ ID NO:11); and a light chain CDR3 comprising GQSHSYPLT (SEQ ID NO:12). In some embodiments, an agent (e.g., an antibody) that specifically binds C3 comprises: (a) a heavy chain CDR1 comprising GYTFTDFYMD (SEQ ID NO:7); a heavy chain CDR2 comprising YIYPHEGGTTYNQQFTG (SEQ ID NO:16), and a heavy chain CDR3 comprising RGGFDFDY (SEQ ID NO:9); and (b) a light chain CDR1 comprising KASENVDTYVS (SEQ ID NO:10); a light chain CDR2 comprising GASNRYT (SEQ ID NO:11); and a light chain CDR3 comprising GQSHSYPLT (SEQ ID NO:12). In some embodiments, an agent (e.g., an antibody) that specifically binds C3 comprises: (a) a heavy chain CDR1 comprising GYTFTDFYMD (SEQ ID NO:7); a heavy chain CDR2 comprising YIYPHQGGTTYNQQFTG (SEQ ID NO:17), and a heavy chain CDR3 comprising RGGFDFDY (SEQ ID NO:9); and (b) a light chain CDR1 comprising KASENVDTYVS (SEQ ID NO:10); a light chain CDR2 comprising GASNRYT (SEQ ID NO:11); and a light chain CDR3 comprising GQSHSYPLT (SEQ ID NO:12). In some embodiments, the agent is an antibody.

In certain embodiments, an agent (e.g., an antibody) that specifically binds C3 comprises: a heavy chain variable region comprising heavy chain CDRs 1, 2, and 3, and a light chain variable region comprising light chain CDRs 1, 2, and 3, wherein heavy chain CDR1 comprises GYTFTDFYMD (SEQ ID NO:7), heavy chain CDR2 comprises YIYPHNGGTTYNQNFTG (SEQ ID NO:8), heavy chain CDR3 comprises RGGFDFDY (SEQ ID NO:9), light chain CDR1 comprises KASENVDTYVS (SEQ ID NO:10), light chain CDR2 comprises GASNRYT (SEQ ID NO:11), and light chain CDR3 comprises GQSHSYPLT (SEQ ID NO:12). In certain embodiments, an agent (e.g., an antibody) that specifically binds C3 comprises: a heavy chain variable region comprising heavy chain CDRs 1, 2, and 3, and a light chain variable region comprising light chain CDRs 1, 2, and 3, wherein heavy chain CDR1 comprises GYTFTDFYMD (SEQ ID NO:7), heavy chain CDR2 comprises YIYPHNGGTTYNQQFTG (SEQ ID NO:13), heavy chain CDR3 comprises RGGFDFDY (SEQ ID NO:9), light chain CDR1 comprises KASENVDTYVS (SEQ ID NO:10), light chain CDR2 comprises GASNRYT (SEQ ID NO:11), and light chain CDR3 comprises GQSHSYPLT (SEQ ID NO:12). In certain embodiments, an agent (e.g., an antibody) that specifically binds C3 comprises: a heavy chain variable region comprising heavy chain CDRs 1, 2, and 3, and a light chain variable region comprising light chain CDRs 1, 2, and 3, wherein heavy chain CDR1 comprises GYTFTDFYMD (SEQ ID NO: 7), heavy chain CDR2 comprises YIYPHNAGTTYNQQFTG (SEQ ID NO:14), heavy chain CDR3 comprises RGGFDFDY (SEQ ID NO:9), light chain CDR1 comprises KASENVDTYVS (SEQ ID NO:10), light chain CDR2 comprises GASNRYT (SEQ ID NO:11), and light chain CDR3 comprises GQSHSYPLT (SEQ ID NO:12). In certain embodiments, an agent (e.g., an antibody) that specifically binds C3 comprises: a heavy chain variable region comprising heavy chain CDRs 1, 2, and 3, and a light chain variable region comprising light chain CDRs 1, 2, and 3, wherein heavy chain CDR1 comprises GYTFTDFYMD (SEQ ID NO:7), heavy chain CDR2 comprises YIYPHNTGTTYNQQFTG (SEQ ID NO:15), heavy chain CDR3 comprises RGGFDFDY (SEQ ID NO:9), light chain CDR1 comprises KASENVDTYVS (SEQ ID NO:10), light chain CDR2 comprises GASNRYT (SEQ ID NO: 11), and light chain CDR3 comprises GQSHSYPLT (SEQ ID NO:12). In certain embodiments, an agent (e.g., an antibody) that specifically binds C3 comprises: a heavy chain variable region comprising heavy chain CDRs 1, 2, and 3, and a light chain variable region comprising light chain CDRs 1, 2, and 3, wherein heavy chain CDR1 comprises GYTFTDFYMD (SEQ ID NO:7), heavy chain CDR2 comprises YIYPHEGGTTYNQQFTG (SEQ ID NO:16), heavy chain CDR3 comprises RGGFDFDY (SEQ ID NO:9), light chain CDR1 comprises KASENVDTYVS (SEQ ID NO:10), light chain CDR2 comprises GASNRYT (SEQ ID NO:11), and light chain CDR3 comprises GQSHSYPLT (SEQ ID NO:12). In certain embodiments, an agent (e.g., an antibody) that specifically binds C3 comprises: a heavy chain variable region comprising heavy chain CDRs 1, 2, and 3, and a light chain variable region comprising light chain CDRs 1, 2, and 3, wherein heavy chain CDR1 comprises GYTFTDFYMD (SEQ ID NO:7), heavy chain CDR2 comprises YIYPHQGGTTYNQQFTG (SEQ ID NO:17), heavy chain CDR3 comprises RGGFDFDY (SEQ ID NO:9), light chain CDR1 comprises KASENVDTYVS (SEQ ID NO:10), light chain CDR2 comprises GASNRYT (SEQ ID NO:11), and light chain CDR3 comprises GQSHSYPLT (SEQ ID NO:12).

In some embodiments, an agent (e.g., an antibody) that specifically binds C3 further comprises (a) a heavy chain framework region (FR) 1, a heavy chain FR2, a heavy chain FR3, and a heavy chain FR4; and/or (b) a light chain FR1, a light chain FR2, a light chain FR3, and a light chain FR4. In some embodiments, an agent (e.g., an antibody) that specifically binds C3 comprises a heavy chain FR1, a heavy chain FR2, a heavy chain FR3, and a heavy chain FR4. In some embodiments, an agent comprises a light chain FR1, a light chain FR2, a light chain FR3, and a light chain FR4. In some embodiments, an agent (e.g., an antibody) that specifically binds C3 comprises (a) a heavy chain FR1, a heavy chain FR2, a heavy chain FR3, and a heavy chain FR4; and (b) a light chain FR1, a light chain FR2, a light chain FR3, and a light chain FR4

In some embodiments, an agent (e.g., an antibody) that specifically binds C3 comprises: (a) a heavy chain variable region having at least 90% sequence identity to SEQ ID NO:18, SEQ ID NO:20, SEQ ID NO:21, SEQ ID NO:22, SEQ ID NO:23, or SEQ ID NO:24; and/or (b) a light chain variable region having at least 90% sequence identity to SEQ ID NO:19 or SEQ ID NO:25. In some embodiments, an agent (e.g., an antibody) that specifically binds C3 comprises a heavy chain variable region having at least 95% sequence identity to SEQ ID NO:18 and a light chain variable region having at least 95% sequence identity to SEQ ID NO:19. In some embodiments, an agent (e.g., an antibody) that specifically binds C3 comprises a heavy chain variable region having at least 95% sequence identity to SEQ ID NO:20 and a light chain variable region having at least 95% sequence identity to SEQ ID NO:25. In some embodiments, an agent (e.g., an antibody) that specifically binds C3 comprises a heavy chain variable region having at least 95% sequence identity to SEQ ID NO:21 and a light chain variable region having at least 95% sequence identity to SEQ ID NO:25. In some embodiments, an agent (e.g., an antibody) that specifically binds C3 comprises a heavy chain variable region having at least 95% sequence identity to SEQ ID NO:22 and a light chain variable region having at least 95% sequence identity to SEQ ID NO:25. In some embodiments, an agent (e.g., an antibody) that specifically binds C3 comprises a heavy chain variable region having at least 95% sequence identity to SEQ ID NO:23 and a light chain variable region having at least 95% sequence identity to SEQ ID NO:25. In some embodiments, an agent (e.g., an antibody) that specifically binds C3 comprises a heavy chain variable region having at least 95% sequence identity to SEQ ID NO:24 and a light chain variable region having at least 95% sequence identity to SEQ ID NO:25. In some embodiments, an agent (e.g., an antibody) that specifically binds C3 comprises a heavy chain variable region comprising SEQ ID NO:18 and a light chain variable region comprising SEQ ID NO:19. In some embodiments, an agent (e.g., an antibody) that specifically binds C3 comprises a heavy chain variable region comprising SEQ ID NO:20 and a light chain variable region comprising SEQ ID NO:25. In some embodiments, an agent (e.g., an antibody) that specifically binds C3 comprises a heavy chain variable region comprising SEQ ID NO:21 and a light chain variable region comprising SEQ ID NO:25. In some embodiments, an agent (e.g., an antibody) that specifically binds C3 comprises a heavy chain variable region comprising SEQ ID NO:22 and a light chain variable region comprising SEQ ID NO:25. In some embodiments, an agent (e.g., an antibody) that specifically binds C3 comprises a heavy chain variable region comprising SEQ ID NO:23 and a light chain variable region comprising SEQ ID NO:25. In some embodiments, an agent (e.g., an antibody) that specifically binds C3 comprises a heavy chain variable region comprising SEQ ID NO:24 and a light chain variable region comprising SEQ ID NO:25. In some embodiments, the agent is an antibody.

In some embodiments, an agent (e.g., an antibody) that specifically binds C3 comprises the heavy chain CDR1, CDR2, and CDR3, and/or the light chain CDR1, CDR2, and CDR3 from: (a) the antibody designated 38G10 that comprises a heavy chain variable region comprising SEQ ID NO:18 and a light chain variable region comprising SEQ ID NO:19; (b) the antibody designated Hz38G10 that comprises a heavy chain variable region comprising SEQ ID NO:20 and a light chain variable region comprising SEQ ID NO:25; (c) the antibody designated Hz38G10(G56A) that comprises a heavy chain variable region comprising SEQ ID NO:21 and a light chain variable region comprising SEQ ID NO:25; (d) the antibody designated Hz38G10(G56T) that comprises a heavy chain variable region comprising SEQ ID NO:22 and a light chain variable region comprising SEQ ID NO:25; (e) the antibody designated Hz38G10(N55E) that comprises a heavy chain variable region comprising SEQ ID NO:23 and a light chain variable region comprising SEQ ID NO:25, or (f) the antibody designated Hz38G10(N55Q) that comprises a heavy chain variable region comprising SEQ ID NO:24 and a light chain variable region comprising SEQ ID NO:25.

In some embodiments, an agent (e.g., an antibody) that specifically binds C3 comprises the CDR1, CDR2, and CDR3 from a heavy chain variable region and the CDR1, CDR2, and CDR3 from a light chain variable region, wherein each CDR is defined in accordance with the Exemplary definition, the Chothia definition, the AbM definition, the Kabat definition, or the contact definition. Thus, in some embodiments, an agent (e.g., an antibody) that specifically binds C3 comprises the CDR1, CDR2, and CDR3 from a heavy chain variable region comprising SEQ ID NO:18 and the CDR1, CDR2, and CDR3 from a light chain variable region comprising SEQ ID NO:19. In some embodiments, an agent (e.g., an antibody) that specifically binds C3 comprises the CDR1, CDR2, and CDR3 from a heavy chain variable region comprising SEQ ID NO:20 and the CDR1, CDR2, and CDR3 from a light chain variable region comprising SEQ ID NO:25. In some embodiments, an agent (e.g., an antibody) that specifically binds C3 comprises the CDR1, CDR2, and CDR3 from a heavy chain variable region comprising SEQ ID NO:21 and the CDR1, CDR2, and CDR3 from a light chain variable region comprising SEQ ID NO:25. In some embodiments, an agent (e.g., an antibody) that specifically binds C3 comprises the CDR1, CDR2, and CDR3 from a heavy chain variable region comprising SEQ ID NO:22 and the CDR1, CDR2, and CDR3 from a light chain variable region comprising SEQ ID NO:25. In some embodiments, an agent (e.g., an antibody) that specifically binds C3 comprises the CDR1, CDR2, and CDR3 from a heavy chain variable region comprising SEQ ID NO:23 and the CDR1, CDR2, and CDR3 from a light chain variable region comprising SEQ ID NO:25. In some embodiments, an agent (e.g., an antibody) that specifically binds C3 comprises the CDR1, CDR2, and CDR3 from a heavy chain variable region comprising SEQ ID NO:24 and the CDR1, CDR2, and CDR3 from a light chain variable region comprising SEQ ID NO:25.

In some embodiments, a C3-binding agent is an antibody that comprises a heavy chain of SEQ ID NO:27 and/or a light chain of SEQ ID NO:31. In some embodiments, a C3-binding agent is an antibody that comprises a heavy chain of SEQ ID NO:27 and a light chain of SEQ ID NO:31. In some embodiments, a C3-binding agent is an antibody that comprises a heavy chain of SEQ ID NO:29 and/or a light chain of SEQ ID NO:31. In some embodiments, a C3-binding agent is an antibody that comprises a heavy chain of SEQ ID NO:29 and a light chain of SEQ ID NO:31.

In certain embodiments, an agent (e.g., an antibody) that specifically binds C3 comprises heavy chain CDRs 1, 2, and 3 of a heavy chain variable region comprising the amino acid sequence set forth in SEQ ID NO:91. In certain embodiments, an agent (e.g., an antibody) that specifically binds C3 comprises light chain CDRs 1, 2, and 3 of a light chain variable region comprising the amino acid sequence set forth in SEQ ID NO:92. In certain embodiments, an agent (e.g., an antibody) that specifically binds C3 comprises heavy chain CDRs 1, 2, and 3 of a heavy chain variable region comprising the amino acid sequence set forth in SEQ ID NO:91, and light chain CDRs 1, 2, and 3 of a light chain variable region comprising the amino acid sequence set forth in SEQ ID NO:92. In some embodiments, an agent (e.g., an antibody) that specifically binds C3 comprises a heavy chain variable region comprising heavy chain CDRs 1, 2, and 3, wherein heavy chain CDR1 comprises GYSFTGYNMN (SEQ ID NO:38), heavy chain CDR2 comprises NINPYYGSTNYNQKFKG (SEQ ID NO:39), and heavy chain CDR3 comprises GYYGGNYPFAY (SEQ ID NO:40). In some embodiments, an agent (e.g., an antibody) that specifically binds C3 comprises a light chain variable region comprising light chain CDRs 1, 2, and 3, wherein light chain CDR1 comprises RASENIYSYLA (SEQ ID NO:41), light chain CDR2 comprises NAKTLAE (SEQ ID NO:42), and light chain CDR3 comprises QHYYGTPYT (SEQ ID NO:43). In some embodiments, an agent (e.g., an antibody) that specifically binds C3 comprises a heavy chain variable region comprising heavy chain CDRs 1, 2, and 3 and a light chain variable region comprising light chain CDRs 1, 2, and 3, wherein heavy chain CDR1 comprises GYSFTGYNMN (SEQ ID NO:38), heavy chain CDR2 comprises NINPYYGSTNYNQKFKG (SEQ ID NO:39), heavy chain CDR3 comprises GYYGGNYPFAY (SEQ ID NO:40), light chain CDR1 comprises RASENIYSYLA (SEQ ID NO:41), light chain CDR2 comprises NAKTLAE (SEQ ID NO:42), and light chain CDR3 comprises QHYYGTPYT (SEQ ID NO:43).

In certain embodiments, an agent (e.g., an antibody) that specifically binds C3 comprises heavy chain CDRs 1, 2, and 3 of a heavy chain variable region comprising the amino acid sequence set forth in SEQ ID NO:93. In certain embodiments, an agent (e.g., an antibody) that specifically binds C3 comprises light chain CDRs 1, 2, and 3 of a light chain variable region comprising the amino acid sequence set forth in SEQ ID NO:94. In certain embodiments, an agent (e.g., an antibody) that specifically binds C3 comprises heavy chain CDRs 1, 2, and 3 of a heavy chain variable region comprising the amino acid sequence set forth in SEQ ID NO:93, and light chain CDRs 1, 2, and 3 of a light chain variable region comprising the amino acid sequence set forth in SEQ ID NO:94. In some embodiments, an agent (e.g., an antibody) that specifically binds C3 comprises a heavy chain variable region comprising heavy chain CDRs 1, 2, and 3, wherein heavy chain CDR1 comprises GYSFTGYNMN (SEQ ID NO:38), heavy chain CDR2 comprises NINPYYDSTSYNQKFKG (SEQ ID NO:44), and heavy chain CDR3 comprises ENYDFVGFAY (SEQ ID NO:45). In some embodiments, an agent (e.g., an antibody) that specifically binds C3 comprises a light chain variable region comprising light chain CDRs 1, 2, and 3, wherein light chain CDR1 comprises RASSSVSYMH (SEQ ID NO:46), light chain CDR2 comprises VTSNLAS (SEQ ID NO:47), and light chain CDR3 comprises QQWSTNPLT (SEQ ID NO:48). In some embodiments, an agent (e.g., an antibody) that specifically binds C3 comprises a heavy chain variable region comprising heavy chain CDRs 1, 2, and 3, and a light chain variable region comprising light chain CDRs 1, 2, and 3, wherein heavy chain CDR1 comprises GYSFTGYNMN (SEQ ID NO:38), heavy chain CDR2 comprises NINPYYDSTSYNQKFKG (SEQ ID NO:44), heavy chain CDR3 comprises ENYDFVGFAY (SEQ ID NO:45), light chain CDR1 comprises RASSSVSYMH (SEQ ID NO:46), light chain CDR2 comprises VTSNLAS (SEQ ID NO:47), and light chain CDR3 comprises QQWSTNPLT (SEQ ID NO:48).

In certain embodiments, an agent (e.g., an antibody) that specifically binds C3 comprises heavy chain CDRs 1, 2, and 3 of a heavy chain variable region comprising the amino acid sequence set forth in SEQ ID NO:95. In certain embodiments, an agent (e.g., an antibody) that specifically binds C3 comprises light chain CDRs 1, 2, and 3 of a light chain variable region comprising the amino acid sequence set forth in SEQ ID NO:96. In certain embodiments, an agent (e.g., an antibody) that specifically binds C3 comprises heavy chain CDRs 1, 2, and 3 of a heavy chain variable region comprising the amino acid sequence set forth in SEQ ID NO:95, and light chain CDRs 1, 2, and 3 of a light chain variable region comprising the amino acid sequence set forth in SEQ ID NO:96. In some embodiments, an agent (e.g., an antibody) that specifically binds C3 comprises a heavy chain variable region comprising heavy chain CDRs 1, 2, and 3, wherein heavy chain CDR1 comprises GYSFTGYNMH (SEQ ID NO:49), heavy chain CDR2 comprises NINPYYGTTNSNQKFED (SEQ ID NO:50), and heavy chain CDR3 comprises GIYYYGTGYPYFDF (SEQ ID NO:51). In some embodiments, an agent (e.g., an antibody) that specifically binds C3 comprises a light chain variable region comprising light chain CDRs 1, 2, and 3, wherein light chain CDR1 comprises RASQDINNYLN (SEQ ID NO:52), light chain CDR2 comprises YTSRLHS (SEQ ID NO:53), and light chain CDR3 comprises QQGITLPWT (SEQ ID NO:54). In some embodiments, an agent (e.g., an antibody) that specifically binds C3 comprises a heavy chain variable region comprising heavy chain CDRs 1, 2, and 3, and a light chain variable region comprising light chain CDRs 1, 2, and 3, wherein heavy chain CDR1 comprises GYSFTGYNMH (SEQ ID NO:49), heavy chain CDR2 comprises NINPYYGTTNSNQKFED (SEQ ID NO:50), heavy chain CDR3 comprises GIYYYGTGYPYFDF (SEQ ID NO:51), light chain CDR1 comprises RASQDINNYLN (SEQ ID NO:52), light chain CDR2 comprises YTSRLHS (SEQ ID NO:53), and light chain CDR3 comprises QQGITLPWT (SEQ ID NO:54).

In certain embodiments, an agent (e.g., an antibody) that specifically binds C3 comprises heavy chain CDRs 1, 2, and 3 of a heavy chain variable region comprising the amino acid sequence set forth in SEQ ID NO:97. In certain embodiments, an agent (e.g., an antibody) that specifically binds C3 comprises light chain CDRs 1, 2, and 3 of a light chain variable region comprising the amino acid sequence set forth in SEQ ID NO:98. In certain embodiments, an agent (e.g., an antibody) that specifically binds C3 comprises heavy chain CDRs 1, 2, and 3 of a heavy chain variable region comprising the amino acid sequence set forth in SEQ ID NO:97, and light chain CDRs 1, 2, and 3 of a light chain variable region comprising the amino acid sequence set forth in SEQ ID NO:98. In some embodiments, an agent (e.g., an antibody) that specifically binds C3 comprises a heavy chain variable region comprising heavy chain CDRs 1, 2, and 3, wherein heavy chain CDR1 comprises GYTFTDYWIN (SEQ ID NO:55), heavy chain CDR2 comprises NIYPGSTSANYNEKFKS (SEQ ID NO:56), and heavy chain CDR3 comprises YGYDSWFAY (SEQ ID NO:57). In some embodiments, an agent (e.g., an antibody) that specifically binds C3 comprises a light chain variable region comprising light chain CDRs 1, 2, and 3, wherein light chain CDR1 comprises KSTKSLLNSDGFTYLD (SEQ ID NO:58), light chain CDR2 comprises LVSNRFS (SEQ ID NO:59), and light chain CDR3 comprises FQSNYLPLT (SEQ ID NO:60). In some embodiments, an agent (e.g., an antibody) that specifically binds C3 comprises a heavy chain variable region comprising heavy chain CDRs 1, 2, and 3, and a light chain variable region comprising light chain CDRs 1, 2, and 3, wherein heavy chain CDR1 comprises GYTFTDYWIN (SEQ ID NO:55), heavy chain CDR2 comprises NIYPGSTSANYNEKFKS (SEQ ID NO:56), heavy chain CDR3 comprises YGYDSWFAY (SEQ ID NO:57), light chain CDR1 comprises KSTKSLLNSDGFTYLD (SEQ ID NO:58), light chain CDR2 comprises LVSNRFS (SEQ ID NO:59), and light chain CDR3 comprises FQSNYLPLT (SEQ ID NO:60).

In certain embodiments, an agent (e.g., an antibody) that specifically binds C3 comprises heavy chain CDRs 1, 2, and 3 of a heavy chain variable region comprising the amino acid sequence set forth in SEQ ID NO:99. In certain embodiments, an agent (e.g., an antibody) that specifically binds C3 comprises light chain CDRs 1, 2, and 3 of a light chain variable region comprising the amino acid sequence set forth in SEQ ID NO:100. In certain embodiments, an agent (e.g., an antibody) that specifically binds C3 comprises heavy chain CDRs 1, 2, and 3 of a heavy chain variable region comprising the amino acid sequence set forth in SEQ ID NO:99, and light chain CDRs 1, 2, and 3 of a light chain variable region comprising the amino acid sequence set forth in SEQ ID NO:100. In some embodiments, an agent (e.g., an antibody) that specifically binds C3 comprises a heavy chain variable region comprising heavy chain CDRs 1, 2, and 3, wherein heavy chain CDR1 comprises GYAFNSCWMN (SEQ ID NO:61), heavy chain CDR2 comprises RIYPGDGDTNYNGKFKG (SEQ ID NO:62), and heavy chain CDR3 comprises EGRNYGYEDY (SEQ ID NO:63). In some embodiments, an agent (e.g., an antibody) that specifically binds C3 comprises a light chain variable region comprising light chain CDRs 1, 2, and 3, wherein light chain CDR1 comprises KASQSVDYDGDSYMN (SEQ ID NO:64), light chain CDR2 comprises AASDLES (SEQ ID NO:65), and light chain CDR3 comprises QQANEDPRT (SEQ ID NO:66). In some embodiments, an agent (e.g., an antibody) that specifically binds C3 comprises a heavy chain variable region comprising heavy chain CDRs 1, 2, and 3, and a light chain variable region comprising light chain CDRs 1, 2, and 3, wherein heavy chain CDR1 comprises GYAFNSCWMN (SEQ ID NO:61), heavy chain CDR2 comprises RIYPGDGDTNYNGKFKG (SEQ ID NO:62), heavy chain CDR3 comprises EGRNYGYEDY (SEQ ID NO:63), light chain CDR1 comprises KASQSVDYDGDSYMN (SEQ ID NO:64), light chain CDR2 comprises AASDLES (SEQ ID NO:65), and light chain CDR3 comprises QQANEDPRT (SEQ ID NO:66).

In certain embodiments, an agent (e.g., an antibody) that specifically binds C3 comprises heavy chain CDRs 1, 2, and 3 of a heavy chain variable region comprising the amino acid sequence set forth in SEQ ID NO:101. In certain embodiments, an agent (e.g., an antibody) that specifically binds C3 comprises light chain CDRs 1, 2, and 3 of a light chain variable region comprising the amino acid sequence set forth in SEQ ID NO:102. In certain embodiments, an agent (e.g., an antibody) that specifically binds C3 comprises heavy chain CDRs 1, 2, and 3 of a heavy chain variable region comprising the amino acid sequence set forth in SEQ ID NO:101, and light chain CDRs 1, 2, and 3 of a light chain variable region comprising the amino acid sequence set forth in SEQ ID NO:102. In some embodiments, an agent (e.g., an antibody) that specifically binds C3 comprises a heavy chain variable region comprising heavy chain CDRs 1, 2, and 3, wherein heavy chain CDR1 comprises GFTFSNYAMS (SEQ ID NO:67), heavy chain CDR2 comprises QTISSGGRYTYYPDSVKG (SEQ ID NO:68), and heavy chain CDR3 comprises RYYGNSYWYFDV (SEQ ID NO:69). In some embodiments, an agent (e.g., an antibody) that specifically binds C3 comprises a light chain variable region comprising light chain CDRs 1, 2, and 3, wherein light chain CDR1 comprises KSSQSLLNSGNQKHYLT (SEQ ID NO:70), light chain CDR2 comprises GASTRGS (SEQ ID NO:71), and light chain CDR3 comprises QNDHSYPYT (SEQ ID NO:72). In some embodiments, an agent (e.g., an antibody) that specifically binds C3 comprises a heavy chain variable region comprising heavy chain CDRs 1, 2, and 3, and a light chain variable region comprising light chain CDRs 1, 2, and 3, wherein heavy chain CDR1 comprises GFTFSNYAMS (SEQ ID NO:67), heavy chain CDR2 comprises QTISSGGRYTYYPDSVKG (SEQ ID NO:68), heavy chain CDR3 comprises RYYGNSYWYFDV (SEQ ID NO:69), light chain CDR1 comprises KSSQSLLNSGNQKHYLT (SEQ ID NO:70), light chain CDR2 comprises GASTRGS (SEQ ID NO:71), and light chain CDR3 comprises QNDHSYPYT (SEQ ID NO:72).

In certain embodiments, an agent (e.g., an antibody) that specifically binds C3 comprises heavy chain CDRs 1, 2, and 3 of a heavy chain variable region comprising the amino acid sequence set forth in SEQ ID NO:103. In certain embodiments, an agent (e.g., an antibody) that specifically binds C3 comprises light chain CDRs 1, 2, and 3 of a light chain variable region comprising the amino acid sequence set forth in SEQ ID NO:104. In certain embodiments, an agent (e.g., an antibody) that specifically binds C3 comprises heavy chain CDRs 1, 2, and 3 of a heavy chain variable region comprising the amino acid sequence set forth in SEQ ID NO:103, and light chain CDRs 1, 2, and 3 of a light chain variable region comprising the amino acid sequence set forth in SEQ ID NO:104. In some embodiments, an agent (e.g., an antibody) that specifically binds C3 comprises a heavy chain variable region comprising heavy chain CDRs 1, 2, and 3, wherein heavy chain CDR1 comprises GFTFSSYTMS (SEQ ID NO:73), heavy chain CDR2 comprises YISSGGGTTYYPDTVKG (SEQ ID NO:74), and heavy chain CDR3 comprises RYYRGSSLWYFDV (SEQ ID NO:75). In some embodiments, an agent (e.g., an antibody) that specifically binds C3 comprises a light chain variable region comprising light chain CDRs 1, 2, and 3, wherein light chain CDR1 comprises KSSQSLFNSGSQKNFLT (SEQ ID NO:76), light chain CDR2 comprises WASTRES (SEQ ID NO:77), and light chain CDR3 comprises QNDYSYPLT (SEQ ID NO:78). In some embodiments, an agent (e.g., an antibody) that specifically binds C3 comprises a heavy chain variable region comprising heavy chain CDRs 1, 2, and 3, and a light chain variable region comprising light chain CDRs 1, 2, and 3, wherein heavy chain CDR1 comprises GFTFSSYTMS (SEQ ID NO:73), heavy chain CDR2 comprises YISSGGGTTYYPDTVKG (SEQ ID NO:74), heavy chain CDR3 comprises RYYRGSSLWYFDV (SEQ ID NO:75), light chain CDR1 comprises KSSQSLFNSGSQKNFLT (SEQ ID NO:76), light chain CDR2 comprises WASTRES (SEQ ID NO:77), and light chain CDR3 comprises QNDYSYPLT (SEQ ID NO:78).

In certain embodiments, an agent (e.g., an antibody) that specifically binds C3 comprises heavy chain CDRs 1, 2, and 3 of a heavy chain variable region comprising the amino acid sequence set forth in SEQ ID NO:105. In certain embodiments, an agent (e.g., an antibody) that specifically binds C3 comprises light chain CDRs 1, 2, and 3 of a light chain variable region comprising the amino acid sequence set forth in SEQ ID NO:106. In certain embodiments, an agent (e.g., an antibody) that specifically binds C3 comprises heavy chain CDRs 1, 2, and 3 of a heavy chain variable region comprising the amino acid sequence set forth in SEQ ID NO:105, and light chain CDRs 1, 2, and 3 of a light chain variable region comprising the amino acid sequence set forth in SEQ ID NO:106. In some embodiments, an agent (e.g., an antibody) that specifically binds C3 comprises a heavy chain variable region comprising heavy chain CDRs 1, 2, and 3, wherein heavy chain CDR1 comprises GYSITSGYSLH (SEQ ID NO:79), heavy chain CDR2 comprises YIHYSGSTNYNPSLKS (SEQ ID NO:80), and heavy chain CDR3 comprises AWDYLDY (SEQ ID NO:81). In some embodiments, an agent (e.g., an antibody) that specifically binds C3 comprises a light chain variable region comprising light chain CDRs 1, 2, and 3, wherein light chain CDR1 comprises RASENIYSQLA (SEQ ID NO:82), light chain CDR2 comprises DAKTLAE (SEQ ID NO:83), and light chain CDR3 comprises HHHFGILYT (SEQ ID NO:84). In some embodiments, an agent (e.g., an antibody) that specifically binds C3 comprises a heavy chain variable region comprising heavy chain CDRs 1, 2, and 3, and a light chain variable region comprising light chain CDRs 1, 2, and 3, wherein heavy chain CDR1 comprises GYSITSGYSLH (SEQ ID NO:79), heavy chain CDR2 comprises YIHYSGSTNYNPSLKS (SEQ ID NO:80), heavy chain CDR3 comprises AWDYLDY (SEQ ID NO:81), light chain CDR1 comprises RASENIYSQLA (SEQ ID NO:82), light chain CDR2 comprises DAKTLAE (SEQ ID NO:83), and light chain CDR3 comprises HHHFGILYT (SEQ ID NO:84).

In certain embodiments, an agent (e.g., an antibody) that specifically binds C3 comprises heavy chain CDRs 1, 2, and 3 of a heavy chain variable region comprising the amino acid sequence set forth in SEQ ID NO:107. In certain embodiments, an agent (e.g., an antibody) that specifically binds C3 comprises light chain CDRs 1, 2, and 3 of a light chain variable region comprising the amino acid sequence set forth in SEQ ID NO:108. In certain embodiments, an agent (e.g., an antibody) that specifically binds C3 comprises heavy chain CDRs 1, 2, and 3 of a heavy chain variable region comprising the amino acid sequence set forth in SEQ ID NO:107, and light chain CDRs 1, 2, and 3 of a light chain variable region comprising the amino acid sequence set forth in SEQ ID NO:108. In some embodiments, an agent (e.g., an antibody) that specifically binds C3 comprises a heavy chain variable region comprising heavy chain CDRs 1, 2, and 3, wherein heavy chain CDR1 comprises GYSITSGYYWN (SEQ ID NO:85), heavy chain CDR2 comprises YIRYDGSNNYNPSLKN (SEQ ID NO:86), and heavy chain CDR3 comprises HYGYDGGAFDF (SEQ ID NO:87). In some embodiments, an agent (e.g., an antibody) that specifically binds C3 comprises a light chain variable region comprising light chain CDRs 1, 2, and 3, wherein light chain CDR1 comprises RTSENIYNYLV (SEQ ID NO:88), light chain CDR2 comprises NAKTLEE (SEQ ID NO:89), and light chain CDR3 comprises QHHYGTPFT (SEQ ID NO:90). In some embodiments, an agent (e.g., an antibody) that specifically binds C3 comprises a heavy chain variable region comprising heavy chain CDRs 1, 2, and 3, and a light chain variable region comprising light chain CDRs 1, 2, and 3, wherein heavy chain CDR1 comprises GYSITSGYYWN (SEQ ID NO:85), heavy chain CDR2 comprises YIRYDGSNNYNPSLKN (SEQ ID NO:86), heavy chain CDR3 comprises HYGYDGGAFDF (SEQ ID NO:87), light chain CDR1 comprises RTSENIYNYLV (SEQ ID NO:88), light chain CDR2 comprises NAKTLEE (SEQ ID NO:89), and light chain CDR3 comprises QHHYGTPFT (SEQ ID NO:90).

In another aspect of the disclosure, provided herein is an antibody that competes for binding to C3 with any of the C3-binding agents described herein. In some embodiments, provided herein is an antibody that competes for binding to C3 with a reference antibody, wherein the reference antibody comprises: (a) a heavy chain CDR1 comprising GYTFTDFYMD (SEQ ID NO:7); a heavy chain CDR2 comprising YIYPHNGGTTYNQNFTG (SEQ ID NO:8), and a heavy chain CDR3 comprising RGGFDFDY (SEQ ID NO:9); and (b) a light chain CDR1 comprising KASENVDTYVS (SEQ ID NO:10); a light chain CDR2 comprising GASNRYT (SEQ ID NO:11); and a light chain CDR3 comprising GQSHSYPLT (SEQ ID NO:12). In some embodiments, provided herein is an antibody that competes for binding to C3 with a reference antibody, wherein the reference antibody comprises: (a) a heavy chain CDR1 comprising GYTFTDFYMD (SEQ ID NO:7); a heavy chain CDR2 comprising YIYPHNGGTTYNQQFTG (SEQ ID NO:13), and a heavy chain CDR3 comprising RGGFDFDY (SEQ ID NO:9); and (b) a light chain CDR1 comprising KASENVDTYVS (SEQ ID NO:10); a light chain CDR2 comprising GASNRYT (SEQ ID NO:11); and a light chain CDR3 comprising GQSHSYPLT (SEQ ID NO:12). In some embodiments, provided herein is an antibody that competes for binding to C3 with a reference antibody, wherein the reference antibody comprises: (a) a heavy chain CDR1 comprising GYTFTDFYMD (SEQ ID NO:7); a heavy chain CDR2 comprising YIYPHNAGTTYNQQFTG (SEQ ID NO:14), and a heavy chain CDR3 comprising RGGFDFDY (SEQ ID NO:9); and (b) a light chain CDR1 comprising KASENVDTYVS (SEQ ID NO:10); a light chain CDR2 comprising GASNRYT (SEQ ID NO:11); and a light chain CDR3 comprising GQSHSYPLT (SEQ ID NO:12). In some embodiments, provided herein is an antibody that competes for binding to C3 with a reference antibody, wherein the reference antibody comprises: (a) a heavy chain CDR1 comprising GYTFTDFYMD (SEQ ID NO:7); a heavy chain CDR2 comprising YIYPHNTGTTYNQQFTG (SEQ ID NO:15), and a heavy chain CDR3 comprising RGGFDFDY (SEQ ID NO:9); and (b) a light chain CDR1 comprising KASENVDTYVS (SEQ ID NO:10); a light chain CDR2 comprising GASNRYT (SEQ ID NO:11); and a light chain CDR3 comprising GQSHSYPLT (SEQ ID NO:12). In some embodiments, provided herein is an antibody that competes for binding to C3 with a reference antibody, wherein the reference antibody comprises: (a) a heavy chain CDR1 comprising GYTFTDFYMD (SEQ ID NO:7); a heavy chain CDR2 comprising YIYPHEGGTTYNQQFTG (SEQ ID NO:16), and a heavy chain CDR3 comprising RGGFDFDY (SEQ ID NO:9); and/or (b) a light chain CDR1 comprising KASENVDTYVS (SEQ ID NO:10); a light chain CDR2 comprising GASNRYT (SEQ ID NO:11); and a light chain CDR3 comprising GQSHSYPLT (SEQ ID NO:12). In some embodiments, provided herein is an antibody that competes for binding to C3 with a reference antibody, wherein the reference antibody comprises: (a) a heavy chain CDR1 comprising GYTFTDFYMD (SEQ ID NO:7); a heavy chain CDR2 comprising YIYPHQGGTTYNQQFTG (SEQ ID NO:17), and a heavy chain CDR3 comprising RGGFDFDY (SEQ ID NO:9); and/or (b) a light chain CDR1 comprising KASENVDTYVS (SEQ ID NO:10); a light chain CDR2 comprising GASNRYT (SEQ ID NO:11); and a light chain CDR3 comprising GQSHSYPLT (SEQ ID NO:12).

In some embodiments, provided herein is an antibody that competes for binding to C3 with a reference antibody, wherein the reference antibody comprises a heavy chain variable region comprising SEQ ID NO:18, SEQ ID NO:20, SEQ ID NO:21, SEQ ID NO:22, SEQ ID NO:23, or SEQ ID NO:24; and a light chain variable region comprising SEQ ID NO:19 or SEQ ID NO:25. In some embodiments, a reference antibody comprises a heavy chain variable region comprising SEQ ID NO:18 and a light chain variable region comprising SEQ ID NO:19. In some embodiments, a reference antibody comprises a heavy chain variable region comprising SEQ ID NO:20 and a light chain variable region comprising SEQ ID NO:25. In some embodiments, a reference antibody comprises a heavy chain variable region comprising SEQ ID NO:21 and a light chain variable region comprising SEQ ID NO:25. In some embodiments, a reference antibody comprises a heavy chain variable region comprising SEQ ID NO:22 and a light chain variable region comprising SEQ ID NO:25. In some embodiments, a reference antibody comprises a heavy chain variable region comprising SEQ ID NO:23 and a light chain variable region comprising SEQ ID NO:25. In some embodiments, a reference antibody comprises a heavy chain variable region comprising SEQ ID NO:24 and a light chain variable region comprising SEQ ID NO:25.

In some embodiments, provided herein is a C3-binding agent that binds the same epitope on C3 as an antibody described herein. In some embodiments, provided herein is a C3-binding agent that binds an epitope on C3 that overlaps with the epitope on C3 bound by an antibody described herein. In some embodiments, provided herein is a C3-binding agent that binds the same epitope as an antibody comprising the heavy chain CDR1, CDR2, and CDR3 and the light chain CDR1, CDR2, and CDR3 of an antibody selected from the group consisting of: 38G10, Hz38G10, Hz38G10(N55E), Hz38G10(N55Q), Hz38G10(G56A), or Hz38G10(G56T). In some embodiments, provided herein is a C3-binding agent that binds an epitope that overlaps with the epitope bound by an antibody comprising the heavy chain CDR1, CDR2, and CDR3 and the light chain CDR1, CDR2, and CDR3 of an antibody selected from the group consisting of: 38G10, Hz38G10, Hz38G10(N55E), Hz38G10(N55Q), Hz38G10(G56A), or Hz38G10(G56T). In some embodiments, provided herein is a C3-binding agent that binds the same epitope as an antibody comprising the heavy chain variable region and the light chain variable region from an antibody selected from the group consisting of: 38G10, Hz38G10, Hz38G10(N55E), Hz38G10(N55Q), Hz38G10(G56A), or Hz38G10(G56T). In some embodiments, provided herein is a C3-binding agent that binds an epitope that overlaps with the epitope bound by an antibody comprising the heavy chain variable region and the light chain variable region from an antibody selected from the group consisting of: 38G10, Hz38G10, Hz38G10(N55E), Hz38G10(N55Q), Hz38G10(G56A), or Hz38G10(G56T).

In some embodiments, provided herein is a C3-binding agent that competes with an antibody comprising a heavy chain having the amino acid sequence of SEQ ID NO:27 and a light chain having the amino acid sequence of SEQ ID NO:31 for binding to human C3. In some embodiments, provided herein is a C3-binding agent that competes with an antibody comprising a heavy chain having the amino acid sequence of SEQ ID NO:29 and a light chain having the amino acid sequence of SEQ ID NO:31 for binding to human C3.

In some embodiments of each of the aforementioned aspects and embodiments, as well as other aspects and embodiments described herein, a C3-binding agent is an antibody. In some embodiments, the antibody is a monoclonal antibody. In some embodiments, the antibody is a humanized antibody. In some embodiments, the antibody is a human antibody. In some embodiments, the antibody is a chimeric antibody. In some embodiments, the antibody is a whole or intact antibody. In some embodiments, the antibody is an IgG antibody. In some embodiments, the antibody is an IgG1 antibody, an IgG2 antibody, an IgG3 antibody, or an IgG4 antibody. In some embodiments, the antibody is a bispecific antibody or a multispecific antibody. In some embodiments, the antibody is an antibody fragment (e.g., a C3-binding fragment). In some embodiments, the antibody or antibody fragment is a Fab, Fab′, F(ab′)₂, Fv, scFv, (scFv)₂, single chain antibody, dual variable region antibody, single variable region antibody, linear antibody, nanobody, or a V region antibody. In some embodiments, the antibody is a scFv-CH3, a scFv-Fc fusion, a scFv-HSA fusion, a scFv-PEG fusion, or a scFv-XTEN fusion.

In some embodiments, the antibody is a scFv antibody comprising a heavy chain variable region and a light chain variable region. In some embodiments, the antibody is a disulfide-linked scFv (dsscFv) comprising a heavy chain variable region and a light chain variable region. In some embodiments of the dsscFv, the heavy chain variable region comprises the amino acid sequence of SEQ ID NO:110. In some embodiments of the dsscFv, the heavy chain variable region of the dsscFv comprises the amino acid sequence of SEQ ID NO:111. In some embodiments of the dsscFv, the light chain variable region comprises the amino acid sequence of SEQ ID NO:112. In some embodiments of the dsscFv, the heavy chain variable region comprises the amino acid sequence of SEQ ID NO:110 and the light chain variable region comprises the amino acid sequence of SEQ ID NO:112. In some embodiments of the dsscFv, the heavy chain variable region comprises the amino acid sequence of SEQ ID NO:111 and the light chain variable region comprises the amino acid sequence of SEQ ID NO:112. In some embodiments of the dsscFv, the dsscFv comprises the amino acid sequence of SEQ ID NO:113. In some embodiments of the dsscFv, the dsscFv comprises the amino acid sequence of SEQ ID NO:114. In some embodiments of the dsscFv, the dsscFv comprises the amino acid sequence of SEQ ID NO:119. In some embodiments of the dsscFv, the dsscFv comprises the amino acid sequence of SEQ ID NO:229.

In some embodiments of each of the aforementioned aspects and embodiments, as well as other aspects and embodiments described herein, a C3-binding agent (e.g., an antibody) described herein is an antagonist of C3. In some embodiments, the C3-binding agent is an antagonistic antibody. In some embodiments, a C3-binding agent (e.g., an antibody) inhibits C3 activity. In some embodiments, a C3-binding agent (e.g., an antibody) inhibits activation of the complement system. In some embodiments, a C3-binding agent (e.g., an antibody) inhibits activation of the classical complement pathway. In some embodiments, a C3-binding agent (e.g., an antibody) inhibits activation of the alternative complement pathway. In some embodiments, a C3-binding agent (e.g., an antibody) inhibits activation of the classical complement pathway and the alternative complement pathway.

In another aspect, the disclosure provides compositions comprising a C3-binding agent (e.g., an antibody) described herein.

In another aspect, the disclosure provides pharmaceutical compositions comprising a C3-binding agent (e.g., an antibody) described herein and a pharmaceutically acceptable carrier.

In some embodiments of each of the aforementioned aspects, as well as other aspects and/or embodiments described elsewhere herein, the C3-binding agent (e.g., an antibody) is isolated. In some embodiments, the C3-binding agent (e.g., an antibody) is substantially pure.

In another aspect, the disclosure provides polynucleotides comprising a polynucleotide that encodes a C3-binding agent described herein. In some embodiments, the polynucleotide is isolated. In some embodiments, a vector comprises a polynucleotide that encodes a C3-binding agent described herein. In some embodiments, an isolated cell comprises a polynucleotide that encodes a C3-binding agent described herein. In some embodiments, an isolated cell comprises a vector comprising a polynucleotide that encodes a C3-binding agent described herein. In some embodiments, the disclosure provides a cell comprising a C3-binding agent described herein. In some embodiments, the disclosure provides a cell producing a C3-binding agent described herein. In some embodiments, a cell produces an anti-C3 antibody described herein. In some embodiments, a cell is a monoclonal cell line. In some embodiments, a cell is a hybridoma.

In another aspect, the disclosure provides methods of using the C3-binding agents (e.g., an antibody) described herein. In some embodiments, a method comprises using a composition comprising a C3-binding agent (e.g., an antibody) described herein. In some embodiments, a method comprises using a pharmaceutical composition comprising a C3-binding agent (e.g., an antibody) described herein.

In some embodiments, a method of treating an eye disorder or eye disease in a subject (e.g., a human) comprises administering to the subject a therapeutically effective amount of a C3-binding agent (e.g., an antibody) described herein. In some embodiments, the eye disorder is selected from the group consisting of: macular degeneration (maculopathy), diabetic retinopathy, retinopathy of prematurity, macular dystrophy, retinal dystrophy, uveitis, keratitis, scleritis, retinitis pigmentosa, choroidal neovascularization, retinal neovascularization, and ocular inflammation. In some embodiments, the eye disorder is macular degeneration. In some embodiments, the eye disorder is age-related macular degeneration (AMD). In some embodiments, a method of treating AMD in a subject (e.g., a human) comprises administering to the subject a therapeutically effective amount of a C3-binding agent (e.g., an antibody) described herein. In some embodiments, the AMD is dry AMD. In some embodiments, the AMD is geographic atrophy. In some embodiments, a method of treating geographic atrophy in a subject (e.g., a human) comprises administering to the subject a therapeutically effective amount of a C3-binding agent (e.g., an antibody) described herein.

In some embodiments, a method of inhibiting or suppressing drusen formation in an eye of a subject (e.g., a human) comprises administering to the subject a therapeutically effective amount of a C3-binding agent (e.g., an antibody) described herein.

In some embodiments, a method of inhibiting or suppressing retinal pigment epithelium atrophy in an eye of a subject (e.g., a human) comprises administering to the subject a therapeutically effective amount of a C3-binding agent (e.g., an antibody) described herein.

In some embodiments, a method of inhibiting complement activation in an eye of a subject (e.g., a human) comprises administering to the subject a therapeutically effective amount of a C3-binding agent (e.g., an antibody) described herein.

In some embodiments of the methods described herein, a C3-binding agent (e.g., an antibody) is administrated to an eye of the subject (e.g., a human) by ocular injection, intraocular injection, or intravitreal injection. In some embodiments, a C3-binding agent (e.g., antibody) is administrated to an eye of the subject by intravitreal injection. In some embodiments of the methods described herein, a C3-binding agent (e.g., an antibody) is administrated to an eye of the subject by topical delivery. In some embodiments, a C3-binding agent is administered to an eye of the subject by eye drops.

In some embodiments of the methods described herein, a C3-binding agent is administered to a subject (e.g., a human) as part of a combination therapy. In some embodiments, the combination therapy comprises photodynamic therapy. In some embodiments, the combination therapy comprises photodynamic therapy with verteporfin. In some embodiments, a C3-binding agent is administered to a subject (e.g., a human), wherein the subject is administered one or more additional therapeutic agents. In some embodiments, an additional therapeutic agent is compstatin or an analog or derivative of compstatin (e.g., POT-4; APL-2). In some embodiments, an additional therapeutic agent is a C5 inhibitor. In some embodiments, a C5 inhibitor is selected from the group including, but not limited to, eculizumab, LFG316, or Zimura (anti-C5 aptamer). In some embodiments, an additional therapeutic agent is a properdin inhibitor (e.g., an anti-properdin antibody). In some embodiments, an additional therapeutic agent is a Factor D inhibitor. In some embodiments, a Factor D inhibitor is an anti-Factor D antibody (e.g., lampalizumab). In some embodiments, an additional therapeutic agent is a VEGF inhibitor. In some embodiments, a VEGF inhibitor is selected from the group including, but not limited to, pegaptanib (MACUGEN), ranibizumab (LUCENTIS), bevacizumab (AVASTIN), aflibercept (EYLEA), brolucizumab, and OPT-302. In some embodiments, an additional therapeutic agent is a PDGF inhibitor. In some embodiments, an additional therapeutic agent is a corticosteroid. In some embodiments, an additional therapeutic agent is a neuroprotective agent. In some embodiments, a neuroprotective agent is selected from the group including, but not limited to, ciliary neurotrophic factor (CNTF), tandospirone, and brimonidine.

Also disclosed is the use of a C3-binding agent (e.g., an antibody) described herein in the manufacture of a medicament for treating an eye disorder. Also disclosed is the use of a C3-binding agent (e.g., an antibody) described herein in the manufacture of a medicament for treatment of a C3-associated disease or disorder associated with complement activation.

In some embodiments of each of the aforementioned aspects and embodiments, as well as other aspects and embodiments described herein, the subject is human.

Where aspects or embodiments of the disclosure are described in terms of a Markush group or other grouping of alternatives, the present disclosure encompasses not only the entire group listed as a whole, but also each member of the group individually and all possible subgroups of the main group, and also the main group absent one or more of the group members. The present disclosure also envisages the explicit exclusion of one or more of any of the group members in the claimed disclosure.

BRIEF DESCRIPTION OF THE FIGURES

FIG. 1 . C3a release assay.

FIG. 2 . Alternative Pathway and Classical Pathway Hemolysis Assays. Antibodies 38G10, 3D8, and 15C12 were tested for their ability to inhibit complement activation.

FIG. 3 . Alternative Pathway and Classical Pathway Hemolysis Assays. Antibody Hz38G10 and compstatin derivative (COMP) were tested for their ability to inhibit complement activation.

FIG. 4 . Alternative Pathway and Classical Pathway Hemolysis Assays. Antibody Hz38G10 and a pegylated version of the compstatin derivative (COMP-PEG) were tested for their ability to inhibit complement activation.

FIG. 5 . Binding Site Analysis. Hz38G10 and a compstatin derivative were tested in a competitive binding assay to assess whether the molecules bind to the same or different epitopes.

FIG. 6 . Complement Activation Inhibition. Antibody Hz38G10 was tested for its ability to inhibit complement activation in the eye.

DETAILED DESCRIPTION

The present disclosure provides novel agents, including but not limited to polypeptides such as antibodies, that bind complement component C3. The C3-binding agents include, but are not limited to, polypeptides, antibodies (including antigen-binding fragments thereof), scaffold proteins, and heterodimeric molecules. C3-binding agents include, but are not limited to, antagonists of C3 activity, inhibitors of C3 activity, and/or agents that modulate C3 activity. Related polypeptides, polynucleotides, vectors, compositions comprising the agents, cells comprising the related polynucleotides or vectors, and methods of making the agents are also provided. Methods of using the novel C3-binding agents are also provided.

I. Definitions

Unless otherwise defined herein, technical and scientific terms used in the present description have the meanings that are commonly understood by those of ordinary skill in the art. For purposes of interpreting this specification, the following description of terms will apply and whenever appropriate, terms used in the singular will also include the plural and vice versa. In the event that any description of a term set forth conflicts with any document incorporated herein by reference, the description of the term set forth below shall control.

The term “binding agent” as used herein refers to a molecule which binds a specific antigen or target (e.g., complement component C3). A binding agent may comprise a protein, peptide, nucleic acid, carbohydrate, lipid, or small molecular weight compound. In some embodiments, a binding agent comprises an antibody or an antigen-binding fragment thereof. In some embodiments, a binding agent is an antibody or an antigen-binding fragment thereof. In some embodiments, a binding agent comprises an alternative protein scaffold or artificial scaffold (e.g., a non-immunoglobulin backbone). In some embodiments, a binding agent is a fusion protein comprising an antigen-binding site. In some embodiments, a binding agent is a bispecific or multispecific molecule comprising at least one antigen-binding site.

The term “antibody” as used herein refers to an immunoglobulin molecule, or antigen-binding fragment thereof, that recognizes and binds a target through at least one antigen-binding site. “Antibody” is used herein in the broadest sense and encompasses various antibody structures, including but not limited to, polyclonal antibodies, recombinant antibodies, monoclonal antibodies, chimeric antibodies, humanized antibodies, human antibodies, bispecific antibodies, multispecific antibodies, diabodies, tribodies, tetrabodies, single chain Fv (scFv) antibodies, and antibody fragments as long as they exhibit the desired antigen-binding activity.

The term “intact antibody” or “full-length antibody” refers to an antibody having a structure substantially similar to a native antibody structure. This includes, for example, an antibody comprising two light chains each comprising a variable region and a light chain constant region (CL) and two heavy chains each comprising a variable region and at least heavy chain constant regions CH1, CH2, and CH3.

The term “antibody fragment” as used herein refers to a molecule other than an intact antibody that comprises a portion of an antibody and generally an antigen-binding site. Examples of antibody fragments include, but are not limited to, Fab, Fab′, F(ab′)2, Fv, single chain antibody molecules (e.g., scFv), disulfide-linked scFv (dsscFv), nanobodies, diabodies, tribodies, tetrabodies, minibodies, dual variable domain antibodies (DVD), single variable domain antibodies (e.g., camelid antibodies), and multispecific antibodies formed from antibody fragments.

The term “monoclonal antibody” as used herein refers to a substantially homogenous antibody population involved in the highly specific recognition and binding of a single antigenic determinant or epitope. The term “monoclonal antibody” encompasses intact and full-length monoclonal antibodies as well as antibody fragments (e.g., Fab, Fab′, F(ab′)2, Fv), single chain antibodies (e.g., scFv), fusion proteins comprising an antibody fragment, and any other modified immunoglobulin molecule comprising at least one antigen-binding site. Furthermore, “monoclonal antibody” refers to such antibodies made by any number of techniques, including but not limited to, hybridoma production, phage library display, recombinant expression, and transgenic animals.

The term “chimeric antibody” refers to an antibody in which a portion of the heavy and/or light chain is derived from a first source or species, while the remainder of the heavy and/or light chain is derived from a different source or species.

The term “humanized antibody” as used herein refers to an antibody that comprises a human heavy chain variable region and a light chain variable region wherein the native CDR residues are replaced by residues from corresponding CDRs from a nonhuman antibody (e.g., mouse, rat, rabbit, or nonhuman primate), wherein the nonhuman antibody has the desired specificity, affinity, and/or activity. In some embodiments, one or more framework region residues of the human heavy chain or light chain variable regions are replaced by corresponding residues from nonhuman antibody. Furthermore, humanized antibodies can comprise residues that are not found in the human antibody or in the nonhuman antibody. In some embodiments, these modifications are made to further refine and/or optimize antibody characteristics. In some embodiments, the humanized antibody comprises at least a portion of an immunoglobulin constant region (e.g., CH1, CH2, CH3, Fc), typically that of a human immunoglobulin.

The term “human antibody” as used herein refers to an antibody that possesses an amino acid sequence that corresponds to an antibody produced by a human and/or an antibody that has been made using any of the techniques that are known to those of skill in the art for making human antibodies. These techniques include, but not limited to, phage display libraries, yeast display libraries, transgenic animals, recombinant protein production, and B-cell hybridoma technology.

The terms “epitope” and “antigenic determinant” are used interchangeably herein and refer to that portion of an antigen or target capable of being recognized and bound by a particular antibody. When the antigen or target is a polypeptide, epitopes can be formed both from contiguous amino acids and noncontiguous amino acids juxtaposed by tertiary folding of the protein. Epitopes formed from contiguous amino acids (also referred to as linear epitopes) are typically retained upon protein denaturing, whereas epitopes formed by tertiary folding (also referred to as conformational epitopes) are typically lost upon protein denaturing. An epitope typically includes at least 3, and more usually, at least 5, 6, 7, or 8-10 amino acids in a unique spatial conformation. Epitopes can be predicted using any one of a large number of software bioinformatic tools available on the internet. X-ray crystallography may be used to characterize an epitope on a target protein by analyzing the amino acid residue interactions of an antigen/antibody complex.

The term “specifically binds” as used herein refers to an agent (e.g., an antibody) that interacts more frequently, more rapidly, with greater duration, with greater affinity, or with some combination of the above to a particular antigen, epitope, protein, or target molecule than with alternative substances. A binding agent (e.g. antibody) that specifically binds an antigen can be identified, for example, by immunoassays, ELISAs, SPR (e.g., Biacore), or other techniques known to those of skill in the art. In some embodiments, an agent (e.g., an antibody) that specifically binds an antigen (e.g., human C3) can bind related antigens (e.g., cyno C3). A binding agent that specifically binds an antigen can bind the target antigen at a higher affinity than its affinity for a different antigen. The different antigen can be a related antigen. In some embodiments, a binding agent that specifically binds an antigen can bind the target antigen with an affinity that is at least 20 times greater, at least 30 times greater, at least 40 times greater, at least 50 times greater, at least 60 times greater, at least 70 times greater, at least 80 times greater, at least 90 times greater, or at least 100 times greater, than its affinity for a different antigen. In some embodiments, a binding agent that specifically binds a particular antigen binds a different antigen at such a low affinity that binding cannot be detected using an assay described herein or otherwise known in the art. In some embodiments, affinity is measured using SPR technology in a Biacore system as described herein or as known to those of skill in the art.

The terms “polypeptide” and “peptide” and “protein” are used interchangeably herein and refer to polymers of amino acids of any length. The polymer may be linear or branched, it may comprise modified amino acids, and it may be interrupted by non-amino acids. The terms also encompass an amino acid polymer that has been modified naturally or by intervention; for example, disulfide bond formation, glycosylation, lipidation, acetylation, phosphorylation, or any other manipulation or modification. Also included within the definition are, for example, polypeptides containing one or more analogs of an amino acid, including but not limited to, unnatural amino acids, as well as other modifications known in the art. It is understood that, because the polypeptides of this disclosure may be based upon antibodies, the term “polypeptide” encompasses polypeptides as a single chain and polypeptides of two or more associated chains.

The terms “polynucleotide” and “nucleic acid” and “nucleic acid molecule” are used interchangeably herein and refer to polymers of nucleotides of any length, and include DNA and RNA. The nucleotides can be deoxyribonucleotides, ribonucleotides, modified nucleotides or bases, and/or their analogs, or any substrate that can be incorporated into a polymer by DNA or RNA polymerase.

The terms “identical” or percent “identity” in the context of two or more nucleic acids or polypeptides, refer to two or more sequences or subsequences that are the same or have a specified percentage of nucleotides or amino acid residues that are the same, when compared and aligned (introducing gaps, if necessary) for maximum correspondence, not considering any conservative amino acid substitutions as part of the sequence identity. The percent identity may be measured using sequence comparison software or algorithms or by visual inspection. Various algorithms and software that may be used to obtain alignments of amino acid or nucleotide sequences are well-known in the art. These include, but are not limited to, BLAST, ALIGN, Megalign, BestFit, GCG Wisconsin Package, and variants thereof. In some embodiments, two nucleic acids or polypeptides of the disclosure are substantially identical, meaning they have at least 70%, at least 75%, at least 80%, at least 85%, at least 90%, and in some embodiments at least 95%, 96%, 97%, 98%, 99% nucleotide or amino acid residue identity, when compared and aligned for maximum correspondence, as measured using a sequence comparison algorithm or by visual inspection. In some embodiments, identity exists over a region of the sequences that is at least about 10, at least about 20, at least about 20-40, at least about 40-60 nucleotides or amino acid residues, at least about 60-80 nucleotides or amino acid residues in length or any integral value there between. In some embodiments, identity exists over a longer region than 60-80 nucleotides or amino acid residues, such as at least about 80-100 nucleotides or amino acid residues, and in some embodiments the sequences are substantially identical over the full length of the sequences being compared, for example, (i) the coding region of a nucleotide sequence or (ii) an amino acid sequence.

The phrase “conservative amino acid substitution” as used herein refers to a substitution in which one amino acid residue is replaced with another amino acid residue having a similar side chain. Families of amino acid residues having similar side chains have been generally defined in the art, including basic side chains (e.g., lysine, arginine, histidine), acidic side chains (e.g., aspartic acid, glutamic acid), uncharged polar side chains (e.g., glycine, asparagine, glutamine, serine, threonine, tyrosine, cysteine), nonpolar side chains (e.g., alanine, valine, leucine, isoleucine, proline, phenylalanine, methionine, tryptophan), beta-branched side chains (e.g., threonine, valine, isoleucine) and aromatic side chains (e.g., tyrosine, phenylalanine, tryptophan, histidine). For example, substitution of a phenylalanine for a tyrosine is considered to be a conservative substitution. Generally, conservative substitutions in the sequences of polypeptides and/or antibodies do not abrogate the binding of the polypeptide or antibody to the target binding site. Methods of identifying nucleotide and amino acid conservative substitutions that do not eliminate binding are well-known in the art.

The term “vector” as used herein means a construct, which is capable of delivering, and usually expressing, one or more gene(s) or sequence(s) of interest in a host cell. Examples of vectors include, but are not limited to, viral vectors, naked DNA or RNA expression vectors, plasmid, cosmid, or phage vectors, DNA or RNA expression vectors associated with cationic condensing agents, and DNA or RNA expression vectors encapsulated in liposomes.

The term “isolated” as used herein refers to a polypeptide, soluble protein, antibody, polynucleotide, vector, cell, or composition which is in a form not found in nature. An “isolated” antibody is substantially free of material from the cellular source from which it is derived. In some embodiments, isolated polypeptides, soluble proteins, antibodies, polynucleotides, vectors, cells, or compositions are those which have been purified to a degree that they are no longer in a form in which they are found in nature. In some embodiments, a polypeptide, soluble protein, antibody, polynucleotide, vector, cell, or composition which is isolated is substantially pure. A polypeptide, soluble protein, antibody, polynucleotide, vector, cell, or composition may be isolated from a natural source (e.g., tissue) or from a source such as an engineered cell line.

The term “substantially pure” as used herein refers to material which is at least 50% pure (i.e., free from contaminants), at least 90% pure, at least 95% pure, at least 98% pure, or at least 99% pure.

The term “subject” refers to any animal (e.g., a mammal), including, but not limited to, humans, non-human primates, canines, felines, rabbits, rodents, and the like.

The term “pharmaceutically acceptable” as used herein refers to a substance approved or approvable by a regulatory agency or listed in the U.S. Pharmacopeia, European Pharmacopeia, or other generally recognized pharmacopeia for use in animals, including humans.

The terms “pharmaceutically acceptable excipient, carrier, or adjuvant” or “acceptable pharmaceutical carrier” as used herein refer to an excipient, carrier, or adjuvant that can be administered to a subject (e.g., a human), together with at least one therapeutic agent (e.g., an antibody), and which is generally safe, non-toxic, and has no effect on the pharmacological activity of the therapeutic agent. In general, those of skill in the art and the U.S. FDA consider a pharmaceutically acceptable excipient, carrier, or adjuvant to be an inactive ingredient of any formulation.

The term “pharmaceutical formulation” or “pharmaceutical composition” as used herein refers to a preparation which is in such form as to permit the biological activity of the agent (e.g., an antibody) to be effective. A pharmaceutical formulation or composition generally comprises additional components, such as a pharmaceutically acceptable excipient, carrier, adjuvant, buffers, etc.

The term “effective amount” or “therapeutically effective amount” as used herein refers to the amount of an agent (e.g., an antibody) which is sufficient to reduce and/or ameliorate the severity and/or duration of (i) a disease, disorder or condition in a subject (e.g., a human), and/or (ii) a symptom in a subject (e.g., a human). The term also encompasses an amount of an agent necessary for the (i) reduction or amelioration of the advancement or progression of a given disease, disorder, or condition, (ii) reduction or amelioration of the recurrence, development, or onset of a given disease, disorder, or condition, and/or (iii) the improvement or enhancement of the prophylactic or therapeutic effect(s) of another agent or therapy (e.g., an agent other than the binding agents provided herein).

The term “therapeutic effect” as used herein refers to the effect and/or ability of an agent (e.g., an antibody) to reduce and/or ameliorate the severity and/or duration of (i) a disease, disorder, or condition in a subject (e.g., a human), and/or (ii) a symptom in a subject (e.g., a human). The term also encompasses the ability of an agent to (i) reduce or ameliorate the advancement or progression of a given disease, disorder, or condition, (ii) reduce or ameliorate the recurrence, development, or onset of a given disease, disorder, or condition, and/or (iii) to improve or enhance the prophylactic or therapeutic effect(s) of another agent or therapy (e.g., an agent other than the binding agents provided herein).

The term “treat” or “treatment” or “treating” or “to treat” or “alleviate” or alleviation” or “alleviating” or “to alleviate” as used herein refers to both (1) therapeutic measures that aim to cure, slow down, lessen symptoms of, and/or halt progression of a pathologic condition or disorder and (2) prophylactic or preventative measures that aim to prevent or slow the development of a targeted pathologic condition or disorder. Thus, those in need of treatment include those already with the disorder, those at risk of having/developing the disorder, and those in whom the disorder is to be prevented.

The term “prevent” or “prevention” or “preventing” as used herein refers to the partial or total inhibition of the development, recurrence, onset, or spread of a disease, disorder, or condition, or a symptom thereof in a subject (e.g., a human).

As used herein, reference to “about” or “approximately” a value or parameter includes (and describes) embodiments that are directed to that value or parameter. For example, a description referring to “about X” includes description of “X”.

As used in the present disclosure and claims, the singular forms “a”, “an” and “the” include plural forms unless the context clearly dictates otherwise.

It is understood that wherever embodiments are described herein with the term “comprising” otherwise analogous embodiments described in terms of “consisting of” and/or “consisting essentially of” are also provided. It is also understood that wherever embodiments are described herein with the phrase “consisting essentially of” otherwise analogous embodiments described in terms of “consisting of” are also provided.

The term “and/or” as used in a phrase such as “A and/or B” herein is intended to include both A and B; A or B; A (alone); and B (alone). Likewise, the term “and/or” as used in a phrase such as “A, B, and/or C” is intended to encompass each of the following embodiments: A, B, and C; A, B, or C; A or C; A or B; B or C; A and C; A and B; B and C; A (alone); B (alone); and C (alone).

II. C3-Binding Agents

Amino acid (aa) sequences for human C3 (UniProtKB No. P01024), cynomolgus monkey (“cyno”) (NCBI Ref No. XP_005587776.1), and rat C3 (UniProtKB No. P01026) are provided herein as SEQ ID NO:1, SEQ ID NO:32, and SEQ ID NO:37, respectively. As used herein, reference to amino acid positions of C3 refer to the numbering of amino acid sequences including the signal sequence.

The present disclosure provides agents that bind C3. In some embodiments, a C3-binding agent binds a fragment of C3. In some embodiments, a C3-binding agent binds within a specific region of C3. In some embodiments, a C3-binding agent binds an epitope on C3. In some embodiments, a C3-binding agent binds a linear epitope on C3. In some embodiments, a C3-binding agent binds a conformational epitope on C3. In some embodiments, a C3-binding agent binds human C3 (e.g., SEQ ID NO:1). In some embodiments, a C3-binding agent binds cyno C3 (e.g., SEQ ID NO:32). In some embodiments, a C3-binding agent binds human C3 and cyno C3. In some embodiments, a C3-binding agent binds C3 and does not bind C3b. In some embodiments, a C3-binding agent binds C3 and does not bind C3b at a detectable level. In some embodiments, a C3-binding agent binds C3 with an affinity that is at least 50-fold greater than its affinity for C3b. In some embodiments, a C3-binding agent binds C3 with an affinity that is at least 100-fold greater than its affinity for C3b. In some embodiments, the affinity of a C3-binding agent is measured using SPR technology in a Biacore system.

In some embodiments, the C3-binding agent binds to human C3 (e.g., SEQ ID NO:1) and has at least one or more of the following properties: (a) binds to cyno C3 (e.g., SEQ ID NO:32), (b) inhibits C3 cleavage and C3a release, (c) inhibits activation of the alternative complement pathway, (d) inhibits activation of the classical complement pathway, (e) inhibits activation of the alternative complement pathway and inhibits activation of the classical complement pathway, (f) does not detectably bind to Factor Bb, (g) does not detectably bind to C3d, and (h) does not detectably bind to C3a. In certain embodiments, the C3-binding agent inhibits activation of the classical complement pathway (e.g., as assessed by hemolytic assays). In some embodiments, the C3-binding agent inhibits activation of the alternative complement pathway and classical complement pathway (e.g., as assessed by hemolytic assays).

Assays for determining inhibition of C3 cleavage and C3a release are known in the art. In certain embodiments, the assay is an assay described herein (see, e.g., Example 2). In certain embodiments, the C3-binding agent inhibits C3 cleavage and C3a release at a concentration of 0.1 to 1000 nM. In certain embodiments, a C3-binding agent inhibits C3 cleavage and C3a release if there is a reduction by at least 10%, at least 20%, at least 30%, at least 40%, at least 50%, at least 60%, at least 70%, at least 80%, at least 90%, or at least 95% in the amount of C3 cleavage and C3a release compared to C3 cleavage and C3a release in the absence of the C3-binding agent.

Assays for determining whether a C3-binding agent inhibits activation of the alternative complement pathway or the classical complement pathway are known in the art. In certain embodiments, the assay is an assay described herein (e.g., hemolysis assays; see, e.g., Example 3).

Assays for determining the binding of a C3-binding agent to factor Bb, C3d, or C3a are known in the art. In certain embodiments, the assay is an assay described herein (e.g., BiaCore; see, e.g., Example 5). In certain embodiments, a C3-binding agent is determined to not detectably bind to factor Bb, C3d, or C3a if the C3-binding agent does not bind to factor Bb, C3d, or C3a, respectively, at a concentration of up to 1 μM according to an assay described herein (e.g., BiaCore; see, e.g., Example 5).

In some embodiments, a C3-binding agent is an antibody. In some embodiments, the antibody is a recombinant antibody. In some embodiments, the antibody is a monoclonal antibody. In some embodiments, the antibody is a chimeric antibody. In some embodiments, the antibody is a humanized antibody. In some embodiments, the antibody is a human antibody. In some embodiments, the antibody is an IgA, IgD, IgE, IgG, or IgM antibody. In some embodiments, the antibody is an IgG1 antibody. In some embodiments, the antibody is an IgG2 antibody. In some embodiments, the antibody is an IgG3 antibody. In some embodiments, the antibody is an IgG4 antibody. In some embodiments, the antibody is an antibody fragment comprising an antigen-binding site. In some embodiments, the antibody is a scFv. In some embodiments, the antibody is a disulfide-linked scFv. In some embodiments, the antibody is a bispecific antibody or a multispecific antibody. In some embodiments, the antibody is a monovalent antibody. In some embodiments, the antibody is a monospecific antibody. In some embodiments, the antibody is a bivalent antibody.

In some embodiments, the antibody is isolated. In some embodiments, the antibody is substantially pure.

In some embodiments, a C3-binding agent is a polyclonal antibody. Polyclonal antibodies can be prepared by any method known to those of skill in the art. In some embodiments, polyclonal antibodies are produced by immunizing an animal (e.g., a rabbit, rat, mouse, goat, donkey) with an antigen of interest (e.g., a purified peptide fragment, a recombinant protein, or a fusion protein) using multiple subcutaneous or intraperitoneal injections. In some embodiments, the antigen is conjugated to a carrier such as keyhole limpet hemocyanin (KLH), serum albumin, bovine thyroglobulin, or soybean trypsin inhibitor. The antigen (with or without a carrier protein) is diluted in sterile saline and usually combined with an adjuvant (e.g., Complete or Incomplete Freund's Adjuvant) to form a stable emulsion. After a period of time, polyclonal antibodies are recovered from the immunized animal (e.g., from blood or ascites). In some embodiments, the polyclonal antibodies are purified from serum or ascites according to standard methods in the art including, but not limited to, affinity chromatography, ion-exchange chromatography, gel electrophoresis, and/or dialysis.

In some embodiments, a C3-binding agent is a monoclonal antibody. Monoclonal antibodies can be prepared by any method known to those of skill in the art. In some embodiments, monoclonal antibodies are prepared using hybridoma methods known to one of skill in the art. For example, using a hybridoma method, a mouse, rat, rabbit, hamster, or other appropriate host animal, is immunized as described above. In some embodiments, lymphocytes are immunized in vitro. In some embodiments, the immunizing antigen is a human protein or a fragment thereof. In some embodiments, the immunizing antigen is a mouse protein or a fragment thereof.

Following immunization, lymphocytes are isolated and fused with a suitable myeloma cell line using, for example, polyethylene glycol. The hybridoma cells are selected using specialized media as known in the art and unfused lymphocytes and myeloma cells do not survive the selection process. Hybridomas that produce monoclonal antibodies directed specifically against a chosen antigen can be identified by a variety of methods including, but not limited to, immunoprecipitation, immunoblotting, and in vitro binding assays (e.g., flow cytometry, FACS, ELISA, SPR (e.g., Biacore), and radioimmunoassay). Once hybridoma cells that produce antibodies of the desired specificity, affinity, and/or activity are identified, the clones may be subcloned by limiting dilution techniques. The hybridomas can be propagated either in in vitro culture using standard methods or in vivo as ascites tumors in an animal. The monoclonal antibodies can be purified from the culture medium or ascites fluid according to standard methods in the art including, but not limited to, affinity chromatography, ion-exchange chromatography, gel electrophoresis, and dialysis.

In some embodiments, monoclonal antibodies are made using recombinant DNA techniques as known to one skilled in the art. For example, the polynucleotides encoding an antibody are isolated from mature B-cells or hybridoma cells, such as by RT-PCR using oligonucleotide primers that specifically amplify the genes encoding the heavy and light chains of the antibody, and their sequence is determined using standard techniques. The isolated polynucleotides encoding the heavy and light chains are then cloned into suitable expression vectors which produce the monoclonal antibodies when transfected into host cells such as E. coli, simian COS cells, Chinese hamster ovary (CHO) cells, or myeloma cells that do not otherwise produce immunoglobulin proteins.

In some embodiments, recombinant monoclonal antibodies are isolated from phage display libraries expressing variable domains or CDRs of a desired species. Screening of phage libraries can be accomplished by various techniques known in the art.

In some embodiments, a monoclonal antibody is modified by using recombinant DNA technology to generate alternative antibodies. In some embodiments, the constant domains of the light chain and heavy chain of a mouse monoclonal antibody are substituted for constant regions of a human antibody to generate a chimeric antibody. In some embodiments, the constant regions are truncated or removed to generate a desired antibody fragment of a monoclonal antibody. In some embodiments, site-directed or high-density mutagenesis of the variable region(s) is used to optimize specificity and affinity of a monoclonal antibody.

In some embodiments, a C3-binding agent is a humanized antibody. Various methods for generating humanized antibodies are known in the art. In some embodiments, a humanized antibody comprises one or more amino acid residues that have been introduced into it from a source that is non-human. In some embodiments, humanization is performed by substituting one or more non-human CDR sequences for the corresponding CDR sequences of a human antibody. In some embodiments, the humanized antibodies are constructed by substituting all six CDRs of a non-human antibody (e.g., a mouse antibody) for the corresponding CDRs of a human antibody.

The choice of which human heavy chain variable region and/or light chain variable region is used for generating humanized antibodies can be made based on a variety of factors and by a variety of methods known in the art. In some embodiments, the “best-fit” method is used where the sequence of the variable region of a non-human (e.g., rodent) antibody is screened against the entire library of known human variable region sequences. The human sequence that is most similar to that of the non-human (e.g., rodent) sequence is selected as the human variable region framework for the humanized antibody. In some embodiments, a particular variable region framework derived from a consensus sequence of all human antibodies of a particular subgroup of light or heavy chains is selected as the variable region framework. In some embodiments, the variable region framework sequence is derived from the consensus sequences of the most abundant human subclasses. In some embodiments, human germline genes are used as the source of the variable region framework sequences.

Other methods for humanization include, but are not limited to, a method called “superhumanization” which is described as the direct transfer of CDRs to a human germline framework, a method termed Human String Content (HSC) which is based on a metric of “antibody humanness”, methods based on generation of large libraries of humanized variants (including phage, ribosomal, and yeast display libraries), and methods based on framework region shuffling.

In some embodiments, a C3-binding agent is a human antibody. Human antibodies can be prepared using various techniques known in the art. In some embodiments, human antibodies are generated from immortalized human B lymphocytes immunized in vitro. In some embodiments, human antibodies are generated from lymphocytes isolated from an immunized individual. In any case, cells that produce an antibody directed against a target antigen can be generated and isolated. In some embodiments, a human antibody is selected from a phage library, where that phage library expresses human antibodies. Alternatively, phage display technology may be used to produce human antibodies and antibody fragments in vitro, from immunoglobulin variable region gene repertoires from unimmunized donors. Techniques for the generation and use of antibody phage libraries are well known in the art. Once antibodies are identified, affinity maturation strategies known in the art, including but not limited to, chain shuffling and site-directed mutagenesis, may be employed to generate higher affinity human antibodies. In some embodiments, human antibodies are produced in transgenic mice that contain human immunoglobulin loci. Upon immunization these mice are capable of producing the full repertoire of human antibodies in the absence of endogenous immunoglobulin production.

In some embodiments, a C3-binding agent is a scFv antibody. ScFvs are molecules that comprise a variable heavy chain region and a variable light chain region linked to form a single polypeptide. ScFvs can be produced using recombinant technologies known in the art. In some embodiments, a scFv comprises a polypeptide linker between the heavy chain variable region and the light chain variable region. In some embodiments, the scFv comprises an orientation of (from N- to C-terminus) (i) heavy chain variable region, (ii) linker, and (iii) light chain variable region. In some embodiments, the scFv comprises an orientation (from N- to C-terminus) of (i) light chain variable region, (ii) linker, and (iii) heavy chain variable region. In some embodiments, the scFv is a disulfide-linked scFv (dsscFv), which is a scFv comprising an engineered disulfide bond between the light chain variable region and heavy chain variable region of the scFv. In some embodiments, the heavy chain variable region of the dsscFv comprises the amino acid sequence of SEQ ID NO:110. In some embodiments, the heavy chain variable region of the dsscFv comprises the amino acid sequence of SEQ ID NO:111. In some embodiments, the light chain variable region of the dsscFv comprises the amino acid sequence of SEQ ID NO:112. In some embodiments, the heavy chain variable region of the dsscFv comprises the amino acid sequence of SEQ ID NO: 110 and the light chain variable region of the dsscFv comprises the amino acid sequence of SEQ ID NO:112. In some embodiments, the heavy chain variable region of the dsscFv comprises the amino acid sequence of SEQ ID NO:111 and the light chain variable region of the dsscFv comprises the amino acid sequence of SEQ ID NO:112. In some embodiments, the dsscFv comprises the amino acid sequence of SEQ ID NO:113. In some embodiments, the dsscFv comprises the amino acid sequence of SEQ ID NO:114. In some embodiments, the dsscFv comprises the amino acid sequence of SEQ ID NO:119. In some embodiments, the dsscFv comprises the amino acid sequence of SEQ ID NO:229. In some embodiments, the scFv (e.g., dsscFv) is attached (either directly or indirectly) to a half-life extending moiety such as, e.g., an Fc molecule, a CH3 domain of an immunoglobulin (e.g., CH3 of IgG1), polyethylene glycol (PEG) or a PEG mimetic, XTEN, serum albumin (e.g., human serum albumin), polysicalic acid, N-(2-hydroxypropyl)methacrylamide, or dextran, or is modified by, e.g., hyperglycosylation, to extend the half-life of the scFv (e.g., dsscFv).

A variety of suitable linkers are known to those of skill in the art and are not limited by any specific sequences disclosed herein. In some embodiments, the polypeptide linker is comprised of naturally, or non-naturally, occurring amino acids. In some embodiments, the linker comprises amino acids that allow for flexibility. In some embodiments, the linker comprises amino acids that allow for suitable solubility. In some embodiments, the linker comprises glycine amino acids. In some embodiments, the linker comprises glycine and serine amino acids. In certain embodiments, the linker comprises one or more sets of glycine/serine repeats. In some embodiments, the polypeptide linker is selected from the group consisting of: (GGGGS)_(n) wherein n=1-4 (SEQ ID NO:232), GGGGS (SEQ ID NO:115), GGGGSGGGGS (SEQ ID NO:116), GGGGSGGGGSGGGGS (SEQ ID NO:117), GGGGSGGGGSGGGGSGGGGS (SEQ ID NO:118), and (GGGGA)_(n) wherein n=1-4 (SEQ ID NO:230). In some embodiments, the linker comprises GGGGSGGGGSGGGGS (SEQ ID NO:117).

In some embodiments, a scFv comprises a disulfide bond formed between the heavy chain variable region and the light chain variable region. In some embodiments, a scFv comprises a disulfide bond that increases stability of the scFv molecule. In some embodiments, a scFv comprises a disulfide bond that increases thermostability of the scFv molecule.

In some embodiments, a C3-binding agent is a Fv. A Fv comprises a heavy chain variable region and a light chain variable region. In some embodiments, the Fv is attached (either directly or indirectly) to a half-life extending moiety such as, e.g., an Fc molecule, a CH3 domain of an IgG (e.g., CH3 of IgG1), PEG or a PEG mimetic, XTEN, serum albumin (e.g., human serum albumin), polysicalic acid, N-(2-hydroxypropyl)methacrylamide, or dextran, or is modified, e.g., by hyperglycosylation, to extend the half-life of the Fv.

In some embodiments, a C3-binding agent is a Fab. A Fab is one of the molecules that result from digestion of an immunoglobulin antibody with papain. Fabs are monovalent molecules that comprise a light chain, a heavy chain variable region, a CH1 region, and, optionally, a heavy chain constant region hinge region or a portion thereof. Fabs can be produced using recombinant technologies known in the art. In some embodiments, a Fab comprises a polypeptide linker between the light chain constant region and the heavy chain variable region. In some embodiments, a Fab comprises a polypeptide linker between the heavy chain constant region and the light chain variable region. A variety of suitable linkers are known to those of skill in the art and are not limited by any specific sequences disclosed herein. In certain embodiments, the linker is a linker described herein. In some embodiments, the Fab is attached (either directly or indirectly) to a half-life extending moiety such as, e.g., an Fc molecule, a CH3 domain of an IgG (e.g., CH3 of IgG1), PEG or a PEG mimetic, XTEN, serum albumin (e.g., human serum albumin), polysicalic acid, N-(2-hydroxypropyl)methacrylamide, or dextran, or is modified, e.g., by hyperglycosylation, to extend the half-life of the Fab.

In some embodiments, a Fab comprises a disulfide bond formed between the heavy chain variable region and the light chain variable region. In some embodiments, a Fab comprises a disulfide bond that increases stability of the Fab molecule. In some embodiments, a Fab comprises a disulfide bond that increases thermostability of the Fab molecule.

In some embodiments, a C3-binding agent is a F(ab′)₂. A F(ab′)₂ is one of the molecules that results from digestion of an immunoglobulin antibody with pepsin. A F(ab′)₂ is a divalent molecule that comprises a first light chain in association with a first polypeptide comprising a first heavy chain variable region, a first CH1, and a first hinge region, and a second light chain in association with a second polypeptide comprising a second heavy chain variable region, a second CH1, and a second hinge region, wherein the first hinge region is linked to the second hinge region via at least one disulfide bond. F(ab′)₂s can be produced using recombinant technologies known in the art. In some embodiments, the F(ab′)₂ is attached (either directly or indirectly) to a half-life extending moiety such as, e.g., a CH3 domain of an IgG (e.g., CH3 of IgG1), PEG or a PEG mimetic, XTEN, serum albumin (e.g., human serum albumin), polysicalic acid, N-(2-hydroxypropyl)methacrylamide, or dextran, or is modified, e.g., by hyperglycosylation, to extend the half-life of the F(ab′)₂.

In some embodiments, a F(ab′)₂ comprises a disulfide bond formed between the heavy chain variable region and the light chain variable region. In some embodiments, a F(ab′)₂ comprises a disulfide bond that increases stability of the F(ab′)₂ molecule. In some embodiments, a F(ab′)₂ comprises a disulfide bond that increases thermostability of the F(ab′)₂ molecule.

In some embodiments, a C3-binding agent is a F(ab′). A F(ab′) is a molecule that results from treatment of a F(ab′)₂ with beta-mercaptoethanol. A F(ab′) is a monovalent molecule that comprises a light chain in association with a polypeptide comprising a heavy chain variable region, a CH1, and a hinge region. In some embodiments, the F(ab′) is attached (either directly or indirectly) to a half-life extending moiety such as, e.g., an Fc molecule, a CH3 domain of an IgG (e.g., CH3 of IgG1), PEG or a PEG mimetic, XTEN, serum albumin (e.g., human serum albumin), polysicalic acid, N-(2-hydroxypropyl)methacrylamide, or dextran, or is modified, e.g., by hyperglycosylation, to extend the half-life of the F(ab′).

In some embodiments, a F(ab′) comprises a disulfide bond formed between the heavy chain variable region and the light chain variable region. In some embodiments, a F(ab′) comprises a disulfide bond that increases stability of the F(ab′) molecule. In some embodiments, a F(ab′) comprises a disulfide bond that increases thermostability of the F(ab′) molecule.

In some embodiments, a C3-binding agent is a bispecific antibody. Bispecific antibodies are capable of recognizing and binding at least two different antigens or epitopes. The different epitopes can either be within the same molecule (e.g., two epitopes on C3) or on different molecules (e.g., one epitope on C3 and one epitope on a different target). In some embodiments, a bispecific antibody has enhanced potency as compared to an individual antibody or to a combination of more than one antibody. In some embodiments, a bispecific antibody has reduced toxicity as compared to an individual antibody or to a combination of more than one antibody. It is known to those of skill in the art that any therapeutic agent may have unique pharmacokinetics (PK) (e.g., circulating half-life). In some embodiments, a bispecific antibody has the ability to synchronize the PK of two active binding agents wherein the two individual binding agents have different PK profiles. In some embodiments, a bispecific antibody has the ability to concentrate the actions of two agents in a common area (e.g., tissue) in a subject (e.g., a human). In some embodiments, a bispecific antibody has the ability to concentrate the actions of two agents to a common target (e.g., a specific cell type). In some embodiments, a bispecific antibody has the ability to target the actions of two agents to more than one biological pathway or function. In some embodiments, a bispecific antibody has the ability to target two different cells and bring them closer together.

In some embodiments, a bispecific antibody has decreased toxicity and/or side effects. In some embodiments, a bispecific antibody has decreased toxicity and/or side effects as compared to a mixture of the two individual antibodies or the antibodies as single agents. In some embodiments, a bispecific antibody has an increased therapeutic index. In some embodiments, a bispecific antibody has an increased therapeutic index as compared to a mixture of the two individual antibodies or the antibodies as single agents.

Several techniques for making bispecific antibodies are known by those skilled in the art. In some embodiments, the bispecific antibodies comprise heavy chain constant regions with modifications in the amino acids that are part of the interface between the two heavy chains. These modifications are made to enhance heterodimer formation and generally reduce or eliminate homodimer formation. In some embodiments, the bispecific antibodies are generated using a knobs-into-holes (KIH) strategy. In some embodiments, the bispecific antibodies comprise variant hinge regions incapable of forming disulfide linkages between identical heavy chains (e.g., reduce homodimer formation). In some embodiments, the bispecific antibodies comprise heavy chains with changes in amino acids that result in altered electrostatic interactions. In some embodiments, the bispecific antibodies comprise heavy chains with changes in amino acids that result in altered hydrophobic/hydrophilic interactions.

Bispecific antibodies can be intact antibodies or antibody fragments comprising antigen-binding sites.

C3-binding agents with more than two valencies are also contemplated. In some embodiments, trispecific or tetraspecific antibodies are generated.

In some embodiments, a C3-binding agent is an antibody that binds C3. In some embodiments, an anti-C3 antibody binds human C3. In some embodiments, an anti-C3 antibody binds cyno C3. In some embodiments, an anti-C3 antibody binds human C3 and cyno C3. In some embodiments, an anti-C3 antibody does not bind rat C3. In some embodiments, an anti-C3 antibody binds a C3 epitope. In some embodiments, an anti-C3 antibody does not bind C3a, C3b, C3c, C3d, or iC3b. In some embodiments, an anti-C3 antibody does not bind C3a, C3b, C3c, C3d, and iC3b. In some embodiments, an anti-C3 antibody does not bind C3a. In some embodiments, an anti-C3 antibody does not bind C3c. In some embodiments, an anti-C3 antibody does not bind C3d. In some embodiments, an anti-C3 antibody does not bind iC3b. In some embodiments, an anti-C3 antibody does not bind C3b. In some embodiments, an anti-C3 antibody does not bind C3a, C3b, C3c, C3d, or iC3b at a detectable level. In some embodiments, an anti-C3 antibody binds C3 with an affinity that is at least 20-fold greater than the antibody's affinity to C3a, C3c, C3d, iC3b or C3b. In some embodiments, an anti-C3 antibody binds C3 with an affinity that is at least 50-fold greater than the antibody's affinity to C3a, C3c, C3d, iC3b or C3b. In some embodiments, an anti-C3 antibody binds C3 with an affinity that is at least 100-fold greater than the antibody's affinity to C3a, C3c, C3d, iC3b or C3b. In some embodiments, an anti-C3 antibody binds C3 and does not bind C3b at a detectable level. In some embodiments, an anti-C3 antibody binds C3 with an affinity that is at least 50-fold greater than the antibody's affinity to C3b. In some embodiments, an anti-C3 antibody binds C3 with an affinity that is at least 100-fold greater than the antibody's affinity to C3b.

In some embodiments, a C3-binding agent is an anti-C3 antibody that comprises one, two, three, four, five, and/or six CDRs of any one of the antibodies described herein. In some embodiments, an anti-C3 antibody comprises (i) one, two, and/or three heavy chain CDRs from Table 1A, and/or (ii) one, two, and/or three light chain CDRs from Table 1A. In some embodiments, an anti-C3 antibody comprises (i) three heavy chain CDRs from Table 1A (i.e., a CDR1, a CDR2, and a CDR3), and (ii) three light chain CDRs from Table 1A. In some embodiments, an anti-C3 antibody comprises (i) one, two, and/or three heavy chain CDRs from Table 1B, and/or (ii) one, two, and/or three light chain CDRs from Table 1B. In some embodiments, an anti-C3 antibody comprises (i) three heavy chain CDRs from Table 1B (i.e., a CDR1, a CDR2, and a CDR3), and (ii) three light chain CDRs from Table 1B. In some embodiments, an anti-C3 antibody comprises (i) one, two, and/or three heavy chain CDRs from Table 1C, and/or (ii) one, two, and/or three light chain CDRs from Table 1C. In some embodiments, an anti-C3 antibody comprises (i) three heavy chain CDRs from Table 1C (i.e., a CDR1, a CDR2, and a CDR3), and (ii) three light chain CDRs from Table 1C. In some embodiments, an anti-C3 antibody comprises (i) one, two, and/or three heavy chain CDRs from Table 2, and/or (ii) one, two, and/or three light chain CDRs from Table 2. In some embodiments, an anti-C3 antibody comprises (i) three heavy chain CDRs from Table 2, and (ii) three light chain CDRs from Table 2. In some embodiments, an anti-C3 antibody comprises (i) one, two, and/or three heavy chain CDRs from Table 3, and/or (ii) one, two, and/or three light chain CDRs from Table 3. In some embodiments, an anti-C3 antibody comprises (i) three heavy chain CDRs from Table 3, and (ii) three light chain CDRs from Table 3. In some embodiments, an anti-C3 antibody comprises (i) one, two, and/or three heavy chain CDRs from Table 4, and/or (ii) one, two, and/or three light chain CDRs from Table 4. In some embodiments, an anti-C3 antibody comprises (i) three heavy chain CDRs from Table 4, and (ii) three light chain CDRs from Table 4. In some embodiments, an anti-C3 antibody comprises (i) one, two, and/or three heavy chain CDRs from Table 5, and/or (ii) one, two, and/or three light chain CDRs from Table 5. In some embodiments, an anti-C3 antibody comprises (i) three heavy chain CDRs from Table 5, and (ii) three light chain CDRs from Table 5. In some embodiments, an anti-C3 antibody comprises (i) one, two, and/or three heavy chain CDRs from Table 6, and/or (ii) one, two, and/or three light chain CDRs from Table 6. In some embodiments, an anti-C3 antibody comprises (i) three heavy chain CDRs from Table 6, and (ii) three light chain CDRs from Table 6. In some embodiments, an anti-C3 antibody comprises (i) one, two, and/or three heavy chain CDRs from Table 7, and/or (ii) one, two, and/or three light chain CDRs from Table 7. In some embodiments, an anti-C3 antibody comprises (i) three heavy chain CDRs from Table 7, and (ii) three light chain CDRs from Table 7. In some embodiments, an anti-C3 antibody comprises (i) one, two, and/or three heavy chain CDRs from Table 8, and/or (ii) one, two, and/or three light chain CDRs from Table 8. In some embodiments, an anti-C3 antibody comprises (i) three heavy chain CDRs from Table 8, and (ii) three light chain CDRs from Table 8. In some embodiments, an anti-C3 antibody comprises (i) one, two, and/or three heavy chain CDRs from Table 9, and/or (ii) one, two, and/or three light chain CDRs from Table 9. In some embodiments, an anti-C3 antibody comprises (i) three heavy chain CDRs from Table 9, and (ii) three light chain CDRs from Table 9. In some embodiments, an anti-C3 antibody comprises (i) one, two, and/or three heavy chain CDRs from Table 10, and/or (ii) one, two, and/or three light chain CDRs from Table 10. In some embodiments, an anti-C3 antibody comprises (i) three heavy chain CDRs from Table 10, and (ii) three light chain CDRs from Table 10. In some embodiments, a C3-binding agent is a humanized anti-C3 antibody that comprises (i) one, two, and/or three heavy chain CDRs, and/or (ii) one, two, and/or three light chain CDRs from any one of Tables 1-10.

TABLE 1A Antibody 38G10 Sequences Exemplary Chothia AbM Kabat Contact Heavy GYTFT GYTFT GYTFT DFYMD TDFYM Chain DFYMD DF DFYMD (SEQ D CDR1 (SEQ (SEQ (SEQ ID (SEQ ID ID ID NO: ID NO: NO: NO: 121) NO: 7) 120) 7) 122) Heavy YIYPH YPHNG YIYPH YIYPH WIGYI Chain NGGTT G NGGTT NGGTT YPHNG CDR2 YN (SEQ (SEQ YN GTT QNFTG ID ID QNFTG (SEQ (SEQ NO: NO: (SEQ ID ID 123) 124) ID NO: NO: NO: 125) 8) 8) Heavy RGGFD RGGFD RGGFD RGGFD ARRGG Chain FDY FDY FDY FDY FDFD CDR3 (SEQ (SEQ (SEQ (SEQ (SEQ ID ID ID ID ID NO: NO: NO: NO: NO: 9) 9) 9) 9) 126) Light KASEN KASEN KASEN KASEN DTYVS Chain VDTYV VDTYV VDTYV VDTYV WY CDR1 S S S S (SEQ (SEQ (SEQ (SEQ (SEQ ID ID ID ID ID NO: NO: NO: NO: NO: 127) 10) 10) 10) 10) Light GASNR GASNR GASNR GASNR LLIYG Chain YT YT YT YT ASNRY CDR2 (SEQ (SEQ (SEQ (SEQ (SEQ ID ID ID ID ID NO: NO: NO: NO: NO: 11) 11) 11) 11) 128) Light GQSHS GQSHS GQSHS GQSHS GQSHS Chain YPLT YPLT YPLT YPLT YPL CDR3 (SEQ (SEQ (SEQ (SEQ (SEQ ID ID ID ID ID NO: NO: NO: NO: NO: 12) 12) 12) 12) 129) 38G10 Heavy chain variable region (SEQ ID NO: 18) EVQLQQSGPELVKPGDSVKMSCKASGYTFTDFYMDWV KQSHGKSLEWIGYIYPHNGGTTYNQNFTGKATLTVDK SSNTAYMELHSLTSEDSAVYYCARRGGFDEDYWGQGT TLTVSS 38G10 Light chain variable region (SEQ ID NO: 19) NIVMTQSPKSMSLSVGERVTLRCKASENVDTYVSWYQ QKPEQSPKLLIYGASNRYTGVPDRFTGSGSATEFTLT ISSVQAEDLVGYHCGQSHSYPLTFGAGTKLELK

TABLE 1B  Antibody Hz38G10 Sequences Exemplary Chothia AbM Kabat Contact Heavy GYTFT GYTFT GYTFT DFYMD TDFYM Chain DFYMD DF DFYMD (SEQ D CDR1 (SEQ (SEQ (SEQ ID (SEQ ID ID ID NO: ID NO: NO: NO: 121) NO: 7) 120) 7) 122) Heavy YIYPH YPHNG YIYPH YIYPH WMGYI Chain NGGTT G NGGTT NGGTT YPHN CDR2 YN (SEQ (SEQ YN GGTT QQFTG ID ID QQFTG (SEQ (SEQ NO: NO: (SEQ ID ID 123) 124) ID NO: NO: NO: 130) 13) 13) Heavy RGGFD RGGFD RGGFD RGGFD ARRGG Chain FDY FDY FDY FDY FDFD CDR3 (SEQ (SEQ (SEQ (SEQ (SEQ ID ID ID ID ID NO: NO: NO: NO: NO: 9) 9) 9) 9) 126) Light KASEN KASEN KASEN KASEN DTYVS Chain VDTYV VDTYV VDTYV VDTYV WY CDR1 S S S S (SEQ (SEQ (SEQ (SEQ (SEQ ID ID ID ID ID NO: NO: NO: NO: NO: 127) 10) 10) 10) 10) Light GASNR GASNR GASNR GASNR LLIYG Chain YT YT YT YT ASNRY CDR2 (SEQ (SEQ (SEQ (SEQ (SEQ ID ID ID ID ID NO: NO: NO: NO: NO: 11) 11) 11) 11) 128) Light GQSHS GQSHS GQSHS GQSHS GQSHS Chain YPLT YPLT YPLT YPLT YPL CDR3 (SEQ (SEQ (SEQ (SEQ (SEQ ID ID ID ID ID NO: NO: NO: NO: NO: 12) 12) 12) 12) 129) Hz38G10 Heavy chain variable region (SEQ ID NO: 20) QVQLVQSGAEVKKPGASVKVSCKASGYTFTDFYMDWVR QAPGORLEWMGYIYPHNGGTTYNQQFTGRVTITVDKSA STAYMELSSLRSEDTAVYYCARRGGFDFDYWGQGTLVT VSS Hz38G10 Light chain variable region (SEQ ID NO: 25) DIQMTQSPSSLSASVGDRVTITCKASENVDTYVSWYQQ KPGKAPKLLIYGASNRYTGVPSRFSGSGSGTDFTFTIS SLQPEDIATYHCGQSHSYPLTFGQGTKLEIK

TABLE 1C Antibody HZ38G10 Variant Sequences Exem- plary Chothia AbM Kabat Contact Heavy GYTFT GYTFT GYTFT DFYMD TDFYM Chain DFYMD DF DFYMD (SEQ D CDR1 (SEQ (SEQ (SEQ ID (SEQ ID ID ID NO: ID NO: NO: NO: 121) NO: 7) 120) 7) 122) Variant YIYPH YPHNA YIYPH YIYPH WMGYI Heavy NAGTT G NAGTT NAGTT YPHN Chain YN (SEQ (SEQ YN AGTT CDR2 QQFTG ID ID QQFTG (SEQ (SEQ NO: NO: (SEQ ID ID 131) 132) ID NO: NO: NO: 133) 14) 14) Variant YIYPH YPHNT YIYPH YIYPH WMGYI Heavy NTGTT G NTGTT NTGTT YPHN Chain YN (SEQ (SEQ YN TGTT CDR2 QQFTG ID ID QQFTG (SEQ (SEQ NO: NO: (SEQ ID ID 134) 135) ID NO: NO: NO: 136) 15) 15) Variant YIYPH YPHEG YIYPH YIYPH WMGYI Heavy EGGTT G EGGTT EGGTT YPHE Chain YN (SEQ (SEQ YN GGTT CDR2 QQFTG ID ID QQFTG (SEQ (SEQ NO: NO: (SEQ ID ID 137) 138) ID NO: NO: NO: 139) 16) 16) Variant YIYPH YPHQG YIYPH YIYPH WMGYI Heavy QGGTT G QGGTT QGGTT YPHQ Chain YN (SEQ (SEQ YN GGTT CDR2 QQFTG ID ID QQFTG (SEQ (SEQ NO: NO: (SEQ ID ID 140) 141) ID NO: NO: NO: 142) 17) 17) Heavy RGGFD RGGFD RGGFD RGGFD ARRGG Chain FDY FDY FDY FDY FDFD CDR3 (SEQ (SEQ (SEQ (SEQ (SEQ ID ID ID ID ID NO: NO: NO: NO: NO: 9) 9) 9) 9) 126) Light KASEN KASEN KASEN KASEN DTYVS Chain VDTYV VDTYV VDTYV VDTYV WY CDR1 S S S S (SEQ (SEQ (SEQ (SEQ (SEQ ID ID ID ID ID NO: NO: NO: NO: NO: 127) 10) 10) 10) 10) Light GASNR GASNR GASNR GASNR LLIYG Chain YT YT YT YT ASNRY CDR2 (SEQ (SEQ (SEQ (SEQ (SEQ ID ID ID ID ID NO: NO: NO: NO: NO: 11) 11) 11) 11) 128) Light GQSHS GQSHS GQSHS GQSHS GQSHS Chain YPLT YPLT YPLT YPLT YPL CDR3 (SEQ (SEQ (SEQ (SEQ (SEQ ID ID ID ID ID NO: NO: NO: NO: NO: 12) 12) 12) 12) 129)

TABLE 2 Antibody 3D8 Sequences Exem- plary Chothia AbM Kabat Contact Heavy GYSFT GYSFT GYSFT GYNMN TGYNM Chain GYNMN GY GYNMN (SEQ N CDR1 (SEQ (SEQ (SEQ ID (SEQ ID ID ID NO: ID NO: NO: NO: 144) NO: 38) 143) 38) 145) Heavy NINPY NPYYG NINPY NINPY WIGNI Chain YGSTN S YGSTN YGSTN NPYYG CDR2 YN (SEQ (SEQ YN STN QKFKG ID ID QKFKG (SEQ (SEQ NO: NO: (SEQ ID ID 146) 147) ID NO: NO: NO: 149) 39) 39) Heavy GYYGG GYYGG GYYGG GYYGG ARGYY Chain NYPFA NYPFA NYPFA NYPFA GGNYP CDR3 Y Y Y Y FA(SEQ (SEQ (SEQ (SEQ (SEQ ID ID ID ID ID NO: NO: NO: NO: NO: 150) 40) 40) 40) 40) Light RASEN RASEN RASEN RASEN YSYLA Chain IYSYL IYSYL IYSYL IYSYL WY CDR1 A A A A (SEQ (SEQ (SEQ (SEQ (SEQ ID ID ID ID ID NO: NO: NO: NO: NO: 151) 41) 41) 41) 41) Light NAKTL NAKTL NAKTL NAKTL LLVYN Chain AE AE AE AE AKTLA CDR2 (SEQ (SEQ (SEQ (SEQ (SEQ ID ID ID ID ID NO: NO: NO: NO: NO: 42) 42) 42) 42) 152) Light QHYYG QHYYG QHYYG QHYYG QHYYG Chain TPYT TPYT TPYT TPYT TPY CDR3 (SEQ (SEQ (SEQ (SEQ (SEQ ID ID ID ID ID NO: NO: NO: NO: NO: 43) 43) 43) 43) 153) 3D8 Heavy chain variable region (SEQ ID NO: 91) EIQLQQSGAELVKPGASVKISCKASGYSFTGYNMNWVK QSHGKSLEWIGNINPYYGSTNYNQKFKGKATLTVDKSS TTAYMQLDSLTSEDSAVYYCARGYYGGNYPFAYWGQGT LVTVSA 3D8 Light chain variable region (SEQ ID NO: 92) DIQMTQSPASLSASVGETVTITCRASENIYSYLAWYQQ KQGKSPQLLVYNAKTLAEGVPSRFSGSGSGTQFSLKIN SLQPEDFGSYYCQHYYGTPYTFGGGSKVEIK

TABLE 3  Antibody 3G8 Sequences Exemplary Chothia AbM Kabat Contact Heavy GYSFTG GYSFTG GYSFTG GYNMN TGYNMN Chain YNMN Y YNMN (SEQ (SEQ CDR1 (SEQ (SEQ (SEQ ID ID ID ID ID NO: NO: NO: NO: NO: 144) 145) 38) 143) 38) Heavy NINPYY NPYYDS NINPYY NINPYY WIGNIN Chain DSTSYN (SEQ DSTS DSTSYN PYYDST CDR2 QKFKG ID (SEQ QKFKG S (SEQ NO: ID (SEQ (SEQ ID 154) NO: ID ID NO: 155) NO: NO: 44) 44) 156) Heavy ENYDFV ENYDFV ENYDFV ENYDFV ARENYD Chain GFAY GFAY GFAY GFAY FVGFA CDR3 (SEQ (SEQ (SEQ (SEQ (SEQ ID ID ID ID ID NO: NO: NO: NO: NO: 45) 45) 45) 45) 157) Light RASSSV RASSSV RASSSV RASSSV SYMHWF Chain SYMH SYMH SYMH SYMH (SEQ CDR1 (SEQ (SEQ (SEQ (SEQ ID ID ID ID ID NO: NO: NO: NO: NO: 158) 46) 46) 46) 46) Light VTSNLA VTSNLA VTSNLA VTSNLA PWIYVT Chain S S S S SNLA CDR2 (SEQ (SEQ (SEQ (SEQ (SEQ ID ID ID ID ID NO: NO: NO: NO: NO: 47) 47) 47) 47) 159) Light QQWSTN QQWSTN QQWSTN QQWSTN QQWSTN Chain PLT PLT PLT PLT PL CDR3 (SEQ (SEQ (SEQ (SEQ (SEQ ID ID ID ID ID NO: NO: NO: NO: NO: 48) 48) 48) 48) 160) 3G8 Heavy chain variable region (SEQ ID NO: 93) EIQLQQSGAELVKPGASVKISCMASGYSFTGYNMNWVKQ SHGKGLEWIGNINPYYDSTSYNQKFKGKATLTVDKSSST AYMQLNSLTSEDSAVYYCARENYDFVGFAYWGQGTLVTV SA 3G8 Light chain variable region (SEQ ID NO: 94) QIVLSQSPAILSASPGEKVTMTCRASSSVSYMHWFQQKP GSSPKPWIYVTSNLASGVPPRFSGSGSGTSYSLTISRVE AEDAATYYCQQWSTNPLTFGAGTKLELK

TABLE 4  Antibody 15C12 Sequences Exemplary Chothia AbM Kabat Contact Heavy GYSFTG GYSFTG GYSFTG GYNMH TGYNMH Chain YNMH Y YNMH (SEQ (SEQ CDR1 (SEQ (SEQ (SEQ ID ID ID ID ID NO: NO: NO: NO: NO: 161) 162) 49) 143) 49) Heavy NINPYY NPYYGT (SEQ NINPYY WIGNIN Chain GTTNSN (SEQ ID GTTNSN PYYGTT CDR2 QKFED ID NO: QKFED N (SEQ NO: 164) (SEQ (SEQ ID 163) NINPYY ID ID NO: GTTN NO: NO: 50) 50) 165) Heavy GIYYYG GIYYYG GIYYYG GIYYYG ARGIYY Chain TGYP TGYP TGYP TGYP YGTGYP CDR3 YFDF YFDF YFDF YFDF YFD (SEQ (SEQ (SEQ (SEQ (SEQ ID ID ID ID ID NO: NO: NO: NO: NO: 51) 51) 51) 51) 166) Light RASQDI RASQDI RASQDI RASQDI NNYLNW Chain NNYLN NNYLN NNYLN NNYLN Y CDR1 (SEQ (SEQ (SEQ (SEQ (SEQ ID ID ID ID ID NO: NO: NO: NO: NO: 52) 52) 52) 52) 167) Light YTSRLH YTSRLH YTSRLH YTSRLH LLIYYT Chain S S S S SRLH CDR2 (SEQ (SEQ (SEQ (SEQ (SEQ ID ID ID ID ID NO: NO: NO: NO: NO: 53) 53) 53) 53) 168) Light QQGITL QQGITL QQGITL QQGITL QQGITL Chain PWT PWT PWT PWT PW CDR3 (SEQ (SEQ (SEQ (SEQ (SEQ ID ID ID ID ID NO: NO: NO: NO: NO: 54) 54) 54) 54) 169) 15C12 Heavy chain variable region (SEQ ID NO: 95) EIQLQQSGAELEKPGASVKISCKASGYSFTGYNMHWVKQ SHGKSLEWIGNINPYYGTTNSNQKFEDKATLTVDKSSST AYMQLNSLTSEDSAVYYCARGIYYYGTGYPYFDFWGQGT TLTVSS 15C12 Light chain variable region (SEQ ID NO: 96) DIQMTQTTSSLSASLGDRVTISCRASQDINNYLNWYLQK PDGTVKLLIYYTSRLHSGVPSRFSGSGSGTDYSLTISNL EQEDLATYFCQQGITLPWTFGGGTKLEIK

TABLE 5  Antibody 27A8 Sequences Exemplary Chothia AbM Kabat Contact Heavy GYTFT GYTFT GYTFT DYWIN TDYWI Chain DYWIN DY DYWIN (SEQ N CDR1 (SEQ (SEQ (SEQ ID (SEQ ID ID ID NO: ID NO: NO: NO: 171) NO: 55) 170) 55) 172) Heavy NIYPG YPGST NIYPG NIYPG WIGNI Chain STSAN S STSAN STSAN YPGST CDR2 YN (SEQ (SEQ YN SAN EKFKS ID ID EKFKS (SEQ (SEQ NO: NO: (SEQ ID ID 173) 174) ID NO: NO: NO: 175) 56) 56) Heavy YGYDS YGYDS YGYDS YGYDS ARYGY Chain WFAY WFAY WFAY WFAY DSWFA CDR3 (SEQ (SEQ (SEQ (SEQ (SEQ ID ID ID ID ID NO: NO: NO: NO: NO: 57) 57) 57) 57) 176) Light KSTKS KSTKS KSTKS KSTKS LNSDG Chain LLNSD LLNSD LLNSD LLNSD FTYLD CDR1 G G G G WF FTYLD FTYLD FTYLD FTYLD (SEQ (SEQ (SEQ (SEQ (SEQ ID ID ID ID ID NO: NO: NO: NO: NO: 177) 58) 58) 58) 58) Light LVSNR LVSNR LVSNR LVSNR LLIYL Chain FS FS FS FS VSNRF CDR2 (SEQ (SEQ (SEQ (SEQ (SEQ ID ID ID ID ID NO: NO: NO: NO: NO: 59) 59) 59) 59) 178) Light FQSNY FQSNY FQSNY FQSNY FQSNY Chain LPLT LPLT LPLT LPLT LPL CDR3 (SEQ (SEQ (SEQ (SEQ (SEQ ID ID ID ID ID NO: NO: NO: NO: NO: 60) 60) 60) 60) 179) 27A8 Heavy chain variable region (SEQ ID NO: 97) QVQLLQPGAEFVKPGASVKLSCKASGYTFTDYWINWVKQ RPGQGLEWIGNIYPGSTSANYNEKFKSKATLTIDTSSIT AYMQLSSLTSDDSAVYYCARYGYDSWFAYWGQGTLVTVS A 27A8 Light chain variable region (SEQ ID NO: 98) DVVLTQTPLSLPVNIGDQASISCKSTKSLLNSDGFTYLD WFLQKPGQSPHLLIYLVSNRFSGIPDRESGSGSETDFTL KISRVEAEDLGVYYCFQSNYLPLTFGSGTKLEIK

TABLE 6  Antibody 28C3 Sequences Exemplary Chothia AbM Kabat Contact Heavy GYAFNS GYAFNS GYAFNS SCWMN NSCWMN Chain CWMN C CWMN (SEQ (SEQ CDR1 (SEQ (SEQ (SEQ ID ID ID ID ID NO: NO: NO: NO: NO: 181) 182) 61) 180) 61) Heavy RIYPGD YPGDGD (SEQ RIYPGD WIGRIY Chain GDTNYN (SEQ ID GDTNYN PGDGDT CDR2 GKFKG ID NO: GKFKG N (SEQ NO: 184) (SEQ (SEQ ID 183) RIYPGD ID ID NO: GDTN NO: NO: 62) 62) 185) Heavy EGRNYG EGRNYG EGRNYG EGRNYG AREGRN Chain YEDY YEDY YEDY YEDY YGYED CDR3 (SEQ (SEQ (SEQ (SEQ (SEQ ID ID ID ID ID NO: NO: NO: NO: NO: 63) 63) 63) 63) 186) Light KASQSV KASQSV KASQSV KASQSV DYDGDS Chain DYDG DYDG DYDG DYDG YMNWY CDR1 DSYMN DSYMN DSYMN DSYMN (SEQ (SEQ (SEQ (SEQ (SEQ ID ID ID ID ID NO: NO: NO: NO: NO: 187) 64) 64) 64) 64) Light AASDLE AASDLE AASDLE AASDLE LLIYAA Chain S S S S SDLE CDR2 (SEQ (SEQ (SEQ (SEQ (SEQ ID ID ID ID ID NO: NO: NO: NO: NO: 65) 65) 65) 65) 188) Light QQANED QQANED QQANED QQANED QQANED Chain PRT PRT PRT PRT PR CDR3 (SEQ (SEQ (SEQ (SEQ (SEQ ID ID ID ID ID NO: NO: NO: NO: NO: 66) 66) 66) 66) 189) 28C3 Heavy chain variable region (SEQ ID NO: 99) QVQLQQSGPELVKPGASVKISCKASGYAFNSCWMNWVKQ RPGKGLEWIGRIYPGDGDTNYNGKFKGKATLTADKSSTT AYMQLSSLTSEDSAVYFCAREGRNYGYEDYWGQGTTLTV SS 28C3 Light chain variable region (SEQ ID NO: 100) DIVLTQSPASLAVSLGQRATISCKASQSVDYDGDSYMNW YQQKPGQPPKLLIYAASDLESGIPARFSGSGSGTDFTLN IHPVEEEDAATYYCQQANEDPRTFGGGTKLEIK

TABLE 7  Antibody 38F5 Sequences Exemplary Chothia AbM Kabat Contact Heavy GFTFSN GFTFSN GFTFSN NYAMS SNYAMS Chain YAMS Y YAMS (SEQ (SEQ CDR1 (SEQ (SEQ (SEQ ID ID ID ID ID NO: NO: NO: NO: NO: 191) 192) 67) 190) 67) Heavy QTISSG ISSGGR QTISSG QTISSG WVQTIS Chain GRYTYY Y GRYTY GRYTYY SGGRYT CDR2 P (SEQ (SEQ P Y DSVKG ID ID DSVKG (SEQ (SEQ NO: NO: (SEQ ID ID 193) 194) ID NO: NO: NO: 195) 68) 68) Heavy RYYGNS RYYGNS RYYGNS RYYGNS VRRYYG Chain YWY YWY YWY YWY NSYW CDR3 FDV FDV FDV FDV YFD (SEQ (SEQ (SEQ (SEQ (SEQ ID ID ID ID ID NO: NO: NO: NO: NO: 69) 69) 69) 69) 196) Light KSSQSL KSSQSL KSSQSL KSSQSL LNSGNQ Chain LNSGNQ LNSGNQ LNSGNQ LNSGNQ KHYL CDR1 KHYLT KHYLT KHYLT KHYLT TWY (SEQ (SEQ (SEQ (SEQ (SEQ ID ID ID ID ID NO: NO: NO: NO: NO: 70) 70) 70) 70) 197) Light GASTRG GASTRG GASTRG GASTRG LLIYGA Chain S S S S STRG CDR2 (SEQ (SEQ (SEQ (SEQ (SEQ ID ID ID ID ID NO: NO: NO: NO: NO: 71) 71) 71) 71) 198) Light QNDHSY QNDHSY QNDHSY QNDHSY QNDHSY Chain PYT PYT PYT PYT PY CDR3 (SEQ (SEQ (SEQ (SEQ (SEQ ID ID ID ID ID NO: NO: NO: NO: NO: 72) 72) 72) 72) 199) 38F5 Heavy chain variable region (SEQ ID NO: 101) EVMLVESGGALVKPGGSLKLSCTASGFTFSNYAMSWVRQTPE KRLEWVAQTISSGGRYTYYPDSVKGRFTISRDNARNTLYLQM SSLRSEDTAMYYCVRRYYGNSYWYFDVWGAGTTVTVSS 38F5 Light chain variable region (SEQ ID NO: 102) DIVMTQSPSSLSVSAGEKVTMNCKSSQSLLNSGNQKHYLTWY QQKPGQPPKLLIYGASTRGSGVPDRFTGSGSGTDFTLTISSV QAEDLAVYYCQNDHSYPYTFGGGTKLEIK

TABLE 8 Antibody 62B11 Sequences Exemplary Chothia AbM Kabat Contact Heavy GFTFSS GFTFSS GFTFSS SYTMS SSYTMS Chain YTMS Y YTMS (SEQ (SEQ CDR1 (SEQ (SEQ (SEQ ID ID ID ID ID NO: NO: NO: NO: NO: 201) 202) 73) 200) 73) Heavy YISSGG SSGGGT YISSGG YISSGG WVAYIS Chain GTTYYP (SEQ GTTY GTTYYP SGGGTT CDR2 DTVKG ID (SEQ DTVKG Y (SEQ NO: ID (SEQ (SEQ ID 203) NO: ID ID NO: 204) NO: NO: 74) 74) 205) Heavy RYYRGS RYYRGS RYYRGS RYYRGS ARRYYR Chain SLWY SLWY SLWY SLWY GSSLW CDR3 FDV FDV FDV FDV YFD (SEQ (SEQ (SEQ (SEQ (SEQ ID ID ID ID ID NO: NO: NO: NO: NO: 75) 75) 75) 75) 206) Light KSSQSL KSSQSL KSSQSL KSSQSL FNSGSQ Chain FNSGSQ FNSGSQ FNSGSQ FNSGSQ KNFLTW CDR1 KNFLT KNFLT KNFLT KNFLT Y (SEQ (SEQ (SEQ (SEQ (SEQ ID ID ID ID ID NO: NO: NO: NO: NO: 76) 76) 76) 76) 207) Light WASTRE WASTRE WASTRE WASTRE LLIYWA Chain S S S S STRE CDR2 (SEQ (SEQ (SEQ (SEQ (SEQ ID ID ID ID ID NO: NO: NO: NO: NO: 77) 77) 77) 77) 208) Light QNDYSY QNDYSY QNDYSY QNDYSY QNDYSY Chain PLT PLT PLT PLT PL CDR3 (SEQ (SEQ (SEQ (SEQ (SEQ ID ID ID ID ID NO: NO: NO: NO: NO: 78) 78) 78) 78) 209) 62B11 Heavy chain variable region (SEQ ID NO: 103) EVKLVESGGGLVQPGGSLKLSCAASGFTFSSYTMSWVRQT PEKRLEWVAYISSGGGTTYYPDTVKGRFTVSRDNAKNTLY LQMSSLRSEDTAMYSCARRYYRGSSLWYFDVWGAGTTVTV SS 62B11 Light chain variable region (SEQ ID NO: 104) DIVMTQSPSSLTVTAGEKVTMSCKSSQSLENSGSQKNEL TWYQQRPGQPPKLLIYWASTRESGVPDRFTGSGSGTDFT LTISSVQAEDLAVYYCONDYSYPLTFGAGTKLELK

TABLE 9 Antibody 62F2 Sequences Exemplary Chothia AbM Kabat Contact Heavy GYSITS GYSITS GYSITS SGYSLH TSGYSL Chain GYSLH GY GYSLH (SEQ H CDR1 (SEQ (SEQ (SEQ ID (SEQ ID ID ID NO: ID NO: NO: NO: 211) NO: 79) 210) 79) 212) Heavy YIHYSG HYSGS YIHYSG YIHYSG WMGYIH Chain STNYNP (SEQ STN STNYNP YSGSTN CDR2 SLKS ID (SEQ SLKS (SEQ (SEQ NO: ID (SEQ ID ID 213) NO: ID NO: NO: 214) NO: 215) 80) 80) Heavy AWDYLD AWDYLD AWDYLD AWDYLD ARAWDY Chain Y Y Y Y LD CDR3 (SEQ (SEQ (SEQ (SEQ (SEQ ID ID ID ID ID NO: NO: NO: NO: NO: 81) 81) 81) 81) 216) Light RASENI RASENI RASENI RASENI YSQLAW Chain YSQLA YSQLA YSQLA YSQLA Y CDR1 (SEQ (SEQ (SEQ (SEQ (SEQ ID ID ID ID ID NO: NO: NO: NO: NO: 82) 82) 82) 82) 217) Light DAKTLA DAKTLA DAKTLA DAKTLA LLVYDA Chain E E E E KTLA CDR2 (SEQ (SEQ (SEQ (SEQ (SEQ ID ID ID ID ID NO: NO: NO: NO: NO: 83) 83) 83) 83) 218) Light HHHFGI HHHFGI HHHFGI HHHFGI HHHFGI Chain L L L LYT LY CDR3 YT YT YT (SEQ (SEQ (SEQ (SEQ (SEQ ID ID ID ID ID NO: NO: NO: NO: NO: 84) 219) 84) 84) 84) 62F2 Heavy chain variable region (SEQ ID NO: 105) DVQLQESGPDLVKPSQSLSLTCTVTGYSITSGYSLHWIRQ FPGNKLEWMGYIHYSGSTNYNPSLKSRISITRDTSKNQFF LKLNSVTSEDTATYHCARAWDYLDYWGQGTTLTVSS 62F2 Light chain variable region (SEQ ID NO: 106) DIQMTQSPASLSASVGETVTITCRASENIYSQLAWYQQKQ GKSPQLLVYDAKTLAEGVPSRFSGSGSDTQFSLKIISLQP EDFGRYYCHHHFGILYTFGGGTKLEMK

TABLE 10 Antibody 63A3 Sequences Exemplary Chothia AbM Kabat Contact Heavy GYSITS GYSITS GYSITS SGYYWN TSGYYW Chain GYYWN GY GYYWN (SEQ N CDR1 (SEQ (SEQ (SEQ ID (SEQ ID ID ID NO: ID NO: NO: NO: 220) NO: 85) 210) 85) 221) Heavy YIRYDG RYDGS YIRYDG YIRYDG WMGYIR Chain SNNYN (SEQ SNN SNNYN YDGSNN CDR2 PSLKN ID (SEQ PSLKN (SEQ (SEQ NO: ID (SEQ ID ID 222) NO: ID NO: NO: 223) NO: 224) 86) 86) Heavy HYGYDG HYGYDG HYGYDG HYGYDG ARHYGY Chain GAFDFH GAFDFH GAFDFH GAFDFH DGGAFD CDR3 (SEQ (SEQ (SEQ (SEQ (SEQ ID ID ID ID ID NO: NO: NO: NO: NO: 87) 87) 87) 87) 225) Light RTSENI RTSENI RTSENI RTSENI YNYLVW Chain YNYLV YNYLV YNYLV YNYLV Y CDR1 (SEQ (SEQ (SEQ (SEQ (SEQ ID ID ID ID ID NO: NO: NO: NO: NO: 88) 88) 88) 88) 226) Light NAKTLE NAKTLE NAKTLE NAKTLE LLVYNA Chain E E E E KTLE CDR2 (SEQ (SEQ (SEQ (SEQ (SEQ ID ID ID ID ID NO: NO: NO: NO: NO: 89) 89) 89) 89) 227) Light QHHYGT QHHYGT QHHYGT QHHYGT QHHYGT Chain PFT PFT PFT PFT PF CDR3 (SEQ (SEQ (SEQ (SEQ (SEQ ID ID ID ID ID NO: NO: NO: NO: NO: 90) 90) 90) 90) 228) 63A3 Heavy chain variable region (SEQ ID NO: 107) DVQLQESGPGLVKPSQSLSLTCSVTGYSITSGYYWNWIRQFP GNKLEWMGYIRYDGSNNYNPSLKNRISITRDTSKNQVFLKLN SVTPEDTATYYCARHYGYDGGAFDFWGQGTTLTVSS 63A3 Light chain variable region (SEQ ID NO: 108) DIQMTQSPASLSASVGETVTITCRTSENIYNYLVWYQQKQGK SPQLLVYNAKTLEEGVPSRFSGSGSGTQFSLKVNSLOPEDFG SYYCQHHYGTPFTFGSGTKLEIK

In some embodiments, a C3-binding agent comprises a heavy chain CDR1, CDR2, and CDR3 and/or a light chain CDR1, CDR2, CDR3 from an antibody described herein. In some embodiments, a C3-binding agent comprises a humanized version or humanized variant of an antibody described herein. In some embodiments, a C3-binding agent comprises a heavy chain CDR1, CDR2, and CDR3 and/or a light chain CDR1, CDR2, CDR3 from antibody 38G10 or a humanized version thereof. In some embodiments, a C3-binding agent comprises a heavy chain CDR1, CDR2, and CDR3 and a light chain CDR1, CDR2, CDR3 from antibody 38G10 or a humanized version thereof. In some embodiments, a C3-binding agent comprises a heavy chain CDR1, CDR2, and CDR3 and/or a light chain CDR1, CDR2, CDR3 from antibody Hz38G10 or variants thereof. In some embodiments, a C3-binding agent comprises a heavy chain CDR1, CDR2, and CDR3 and a light chain CDR1, CDR2, CDR3 from antibody Hz38G10 or variants thereof. In some embodiments, a C3-binding agent comprises a heavy chain CDR1, CDR2, and CDR3 and a light chain CDR1, CDR2, CDR3 from antibody 38G10, antibody Hz38G10, or Hz38G10 variants.

In some embodiments, a C3-binding agent comprises a heavy chain CDR1, CDR2, and CDR3 and/or a light chain CDR1, CDR2, and CDR3 from antibody 3D8, a humanized version thereof, or variants thereof. In some embodiments, a C3-binding agent comprises a heavy chain CDR1, a heavy chain CDR2, and a heavy chain CDR3 from antibody 3D8. In other embodiments, a C3-binding agent comprises a light chain CDR1, a light chain CDR2, and a light chain CDR3 from antibody 3D8. In certain embodiments, a C3-binding agent comprises a heavy chain CDR1, a heavy chain CDR2, a heavy chain CDR3, a light chain CDR1, light chain CDR2, and a light chain CDR3 from antibody 3D8. In some embodiments, antibody 3D8 is a humanized version of antibody 3D8. In some embodiments, antibody 3D8 is a variant of antibody 3D8.

In some embodiments, a C3-binding agent comprises a heavy chain CDR1, CDR2, and CDR3 and/or a light chain CDR1, CDR2, and CDR3 from antibody 3G8, a humanized version thereof, or variants thereof. In some embodiments, a C3-binding agent comprises a heavy chain CDR1, a heavy chain CDR2, and a heavy chain CDR3 from antibody 3G8. In other embodiments, a C3-binding agent comprises a light chain CDR1, a light chain CDR2, and a light chain CDR3 from antibody 3G8. In certain embodiments, a C3-binding agent comprises a heavy chain CDR1, a heavy chain CDR2, a heavy chain CDR3, a light chain CDR1, light chain CDR2, and a light chain CDR3 from antibody 3G8. In some embodiments, antibody 3G8 is a humanized version of antibody 3G8. In some embodiments, antibody 3G8 is a variant of antibody 3G8.

In some embodiments, a C3-binding agent comprises a heavy chain CDR1, CDR2, and CDR3 and/or a light chain CDR1, CDR2, CDR3 from antibody 15C12, a humanized version thereof, or variants thereof. In some embodiments, a C3-binding agent comprises a heavy chain CDR1, a heavy chain CDR2, and a heavy chain CDR3 from antibody 15C12. In other embodiments, a C3-binding agent comprises a light chain CDR1, a light chain CDR2, and a light chain CDR3 from antibody 15C12. In certain embodiments, a C3-binding agent comprises a heavy chain CDR1, a heavy chain CDR2, a heavy chain CDR3, a light chain CDR1, light chain CDR2, and a light chain CDR3 from antibody 15C12. In some embodiments, antibody 15C12 is a humanized version of antibody 15C12. In some embodiments, antibody 15C12 is a variant of antibody 15C12.

In some embodiments, a C3-binding agent comprises a heavy chain CDR1, CDR2, and CDR3 and/or a light chain CDR1, CDR2, CDR3 from antibody 27A8, a humanized version thereof, or variants thereof. In some embodiments, a C3-binding agent comprises a heavy chain CDR1, a heavy chain CDR2, and a heavy chain CDR3 from antibody 27A8. In other embodiments, a C3-binding agent comprises a light chain CDR1, a light chain CDR2, and a light chain CDR3 from antibody 27A8. In certain embodiments, a C3-binding agent comprises a heavy chain CDR1, a heavy chain CDR2, a heavy chain CDR3, a light chain CDR1, light chain CDR2, and a light chain CDR3 from antibody 27A8. In some embodiments, antibody 27A8 is a humanized version of antibody 27A8. In some embodiments, antibody 27A8 is a variant of antibody 27A8.

In some embodiments, a C3-binding agent comprises a heavy chain CDR1, CDR2, and CDR3 and/or a light chain CDR1, CDR2, CDR3 from antibody 28C3, a humanized version thereof, or variants thereof. In some embodiments, a C3-binding agent comprises a heavy chain CDR1, a heavy chain CDR2, and a heavy chain CDR3 from antibody 28C3. In other embodiments, a C3-binding agent comprises a light chain CDR1, a light chain CDR2, and a light chain CDR3 from antibody 28C3. In certain embodiments, a C3-binding agent comprises a heavy chain CDR1, a heavy chain CDR2, a heavy chain CDR3, a light chain CDR1, light chain CDR2, and a light chain CDR3 from antibody 28C3. In some embodiments, antibody 28C3 is a humanized version of antibody 28C3. In some embodiments, antibody 28C3 is a variant of antibody 28C3.

In some embodiments, a C3-binding agent comprises a heavy chain CDR1, CDR2, and CDR3 and/or a light chain CDR1, CDR2, CDR3 from antibody 38F5, a humanized version thereof, or variants thereof. In some embodiments, a C3-binding agent comprises a heavy chain CDR1, a heavy chain CDR2, and a heavy chain CDR3 from antibody 38F5. In other embodiments, a C3-binding agent comprises a light chain CDR1, a light chain CDR2, and a light chain CDR3 from antibody 38F5. In certain embodiments, a C3-binding agent comprises a heavy chain CDR1, a heavy chain CDR2, a heavy chain CDR3, a light chain CDR1, light chain CDR2, and a light chain CDR3 from antibody 38F5. In some embodiments, antibody 38F5 is a humanized version of antibody 38F5. In some embodiments, antibody 38F5 is a variant of antibody 38F5.

In some embodiments, a C3-binding agent comprises a heavy chain CDR1, CDR2, and CDR3 and/or a light chain CDR1, CDR2, CDR3 from antibody 62B11, a humanized version thereof, or variants thereof. In some embodiments, a C3-binding agent comprises a heavy chain CDR1, a heavy chain CDR2, and a heavy chain CDR3 from antibody 62B11. In other embodiments, a C3-binding agent comprises a light chain CDR1, a light chain CDR2, and a light chain CDR3 from antibody 62B11. In certain embodiments, a C3-binding agent comprises a heavy chain CDR1, a heavy chain CDR2, a heavy chain CDR3, a light chain CDR1, light chain CDR2, and a light chain CDR3 from antibody 62B11. In some embodiments, antibody 62B11 is a humanized version of antibody 62B11. In some embodiments, antibody 62B11 is a variant of antibody 62B11.

In some embodiments, a C3-binding agent comprises a heavy chain CDR1, CDR2, and CDR3 and/or a light chain CDR1, CDR2, CDR3 from antibody 62F2, a humanized version thereof, or variants thereof. In some embodiments, a C3-binding agent comprises a heavy chain CDR1, a heavy chain CDR2, and a heavy chain CDR3 from antibody 62F2. In other embodiments, a C3-binding agent comprises a light chain CDR1, a light chain CDR2, and a light chain CDR3 from antibody 62F2. In certain embodiments, a C3-binding agent comprises a heavy chain CDR1, a heavy chain CDR2, a heavy chain CDR3, a light chain CDR1, light chain CDR2, and a light chain CDR3 from antibody 62F2. In some embodiments, antibody 62F2 is a humanized version of antibody 62F2. In some embodiments, antibody 62F2 is a variant of antibody 62F2.

In some embodiments, a C3-binding agent comprises a heavy chain CDR1, CDR2, and CDR3 and/or a light chain CDR1, CDR2, CDR3 from antibody 63A3, a humanized version thereof, or variants thereof. In some embodiments, a C3-binding agent comprises a heavy chain CDR1, a heavy chain CDR2, and a heavy chain CDR3 from antibody 63A3. In other embodiments, a C3-binding agent comprises a light chain CDR1, a light chain CDR2, and a light chain CDR3 from antibody 63A3. In certain embodiments, a C3-binding agent comprises a heavy chain CDR1, a heavy chain CDR2, a heavy chain CDR3, a light chain CDR1, light chain CDR2, and a light chain CDR3 from antibody 63A3. In some embodiments, antibody 63A3 is a humanized version of antibody 63A3. In some embodiments, antibody 63A3 is a variant of antibody 63A3.

In some embodiments, a C3-binding agent is an antibody. In some embodiments, a variant of an anti-C3 antibody described herein comprises one to thirty conservative amino acid substitutions. In some embodiments, the variant of the anti-C3 antibody comprises one to twenty-five conservative amino acid substitutions. In some embodiments, the variant of the anti-C3 antibody comprises one to twenty conservative amino acid substitutions. In some embodiments, the variant of the anti-C3 antibody comprises one to fifteen conservative amino acid substitutions. In some embodiments, the variant of the anti-C3 antibody comprises one to ten conservative amino acid substitution(s). In some embodiments, the variant of the anti-C3 antibody comprises one to five conservative amino acid substitution(s). In some embodiments, the variant of the anti-C3 antibody comprises one to three conservative amino acid substitution(s). In some embodiments, the conservative amino acid substitution(s) is in a CDR of the antibody. In some embodiments, the conservative amino acid substitution(s) is not in a CDR of the antibody. In some embodiments, the conservative amino acid substitution(s) is in a framework region of the antibody.

CDRs are defined by a variety of methods/systems by those skilled in the art. These systems and/or definitions have been developed and refined over a number of years and include Kabat, Chothia, IMGT, AbM, and Contact. The Kabat definition is based on sequence variability and generally is the most commonly used. The Chothia definition is based on the location of the structural loop regions. The IMGT system is based on sequence variability and location within the structure of the variable domain. The AbM definition is a compromise between Kabat and Chothia. The Contact definition is based on analyses of the available antibody crystal structures. An Exemplary system is a combination of Kabat and Chothia. Software programs (e.g., abYsis (www.bioinf.org.uk/abysis/sequence_input/key_annotation/key_annotation.cgi)) are available and known to those of skill in the art for analysis of antibody sequences and determination of CDRs.

The specific CDR sequences defined herein are generally based on a combination of Kabat and Chothia definitions (Exemplary system). However, it will be understood that reference to a heavy chain CDR or CDRs and/or a light chain CDR or CDRs of a specific antibody will encompass all CDR definitions as known to those of skill in the art.

In some embodiments, a C3-binding agent (e.g., an antibody) comprises a heavy chain CDR1, CDR2, and CDR3 and a light chain CDR1, CDR2, and CDR3 from the antibody designated 38G10. In some embodiments, a C3-binding agent comprises a heavy chain CDR1, CDR2, and CDR3 from the antibody designated 38G10. In some embodiments, a C3-binding agent comprises a light chain CDR1, CDR2, and CDR3 from the antibody designated 38G10. In some embodiments, a C3-binding agent (e.g., an antibody) comprises a heavy chain CDR1, CDR2, and CDR3 and a light chain CDR1, CDR2, and CDR3 from the antibody designated Hz38G10. In some embodiments, a C3-binding agent comprises a heavy chain CDR1, CDR2, and CDR3 from the antibody designated Hz38G10. In some embodiments, a C3-binding agent (e.g., an antibody) comprises a heavy chain CDR1, CDR2, and CDR3 and a light chain CDR1, CDR2, and CDR3 from the antibody designated Hz38G10(G56A). In some embodiments, a C3-binding agent comprises a heavy chain CDR1, CDR2, and CDR3 from the antibody designated Hz38G10(G56A). In some embodiments, a C3-binding agent (e.g., an antibody) comprises a heavy chain CDR1, CDR2, and CDR3 and a light chain CDR1, CDR2, and CDR3 from the antibody designated Hz38G10(G56T). In some embodiments, a C3-binding agent comprises a heavy chain CDR1, CDR2, and CDR3 from the antibody designated Hz38G10(G56T). In some embodiments, a C3-binding agent (e.g., an antibody) comprises a heavy chain CDR1, CDR2, and CDR3 and a light chain CDR1, CDR2, and CDR3 from the antibody designated Hz38G10(N55E). In some embodiments, a C3-binding agent comprises a heavy chain CDR1, CDR2, and CDR3 from the antibody designated Hz38G10(N55E). In some embodiments, a C3-binding agent (e.g., an antibody) comprises a heavy chain CDR1, CDR2, and CDR3 and a light chain CDR1, CDR2, and CDR3 from the antibody designated Hz38G10(N55Q). In some embodiments, a C3-binding agent comprises a heavy chain CDR1, CDR2, and CDR3 from the antibody designated Hz38G10(N55Q). In some embodiments, a C3-binding agent (e.g., an antibody) comprises a light chain CDR1, CDR2, and CDR3 from the antibody designated Hz38G10, Hz38G10(G56A), Hz38G10(G56T), Hz38G10(N55E), or Hz38G10(N55Q).

In some embodiments, a C3-binding agent (e.g., an antibody) comprises a heavy chain CDR1, CDR2, and CDR3 and a light chain CDR1, CDR2, and CDR3 from Table 1A, Table 1B, or Table 1C.

In certain embodiments, a C3-binding agent (e.g., an antibody) comprises (a) a heavy chain CDR1 comprising SEQ ID NO:7, a heavy chain CDR2 comprising SEQ ID NO:8, a heavy chain CDR3 comprising SEQ ID NO:9, a light chain CDR1 comprising SEQ ID NO:10, a light chain CDR2 comprising SEQ ID NO:11, and a light chain CDR3 comprising SEQ ID NO:12; (b) a heavy chain CDR1 comprising SEQ ID NO:120, a heavy chain CDR2 comprising SEQ ID NO:123, a heavy chain CDR3 comprising SEQ ID NO:9, a light chain CDR1 comprising SEQ ID NO:10, a light chain CDR2 comprising SEQ ID NO:11, and a light chain CDR3 comprising SEQ ID NO:12; (c) a heavy chain CDR1 comprising SEQ ID NO:7, a heavy chain CDR2 comprising SEQ ID NO:124, a heavy chain CDR3 comprising SEQ ID NO:9, a light chain CDR1 comprising SEQ ID NO:10, a light chain CDR2 comprising SEQ ID NO:11, and a light chain CDR3 comprising SEQ ID NO:12; (d) a heavy chain CDR1 comprising SEQ ID NO:121, a heavy chain CDR2 comprising SEQ ID NO:8, a heavy chain CDR3 comprising SEQ ID NO:9, a light chain CDR1 comprising SEQ ID NO:10, a light chain CDR2 comprising SEQ ID NO:11, and a light chain CDR3 comprising SEQ ID NO:12; or (e) a heavy chain CDR1 comprising SEQ ID NO:122, a heavy chain CDR2 comprising SEQ ID NO:125, a heavy chain CDR3 comprising SEQ ID NO:126, a light chain CDR1 comprising SEQ ID NO:127, a light chain CDR2 comprising SEQ ID NO:128, and a light chain CDR3 comprising SEQ ID NO:129. In certain embodiments, a C3-binding agent (e.g., an antibody) comprises (a) a heavy chain CDR1 comprising SEQ ID NO:7, a heavy chain CDR2 comprising SEQ ID NO:13, a heavy chain CDR3 comprising SEQ ID NO:9, a light chain CDR1 comprising SEQ ID NO:10, a light chain CDR2 comprising SEQ ID NO:11, and a light chain CDR3 comprising SEQ ID NO:12; (b) a heavy chain CDR1 comprising SEQ ID NO:120, a heavy chain CDR2 comprising SEQ ID NO:123, a heavy chain CDR3 comprising SEQ ID NO:9, a light chain CDR1 comprising SEQ ID NO:10, a light chain CDR2 comprising SEQ ID NO:11, and a light chain CDR3 comprising SEQ ID NO:12; (c) a heavy chain CDR1 comprising SEQ ID NO:7, a heavy chain CDR2 comprising SEQ ID NO:124, a heavy chain CDR3 comprising SEQ ID NO:9, a light chain CDR1 comprising SEQ ID NO:10, a light chain CDR2 comprising SEQ ID NO:11, and a light chain CDR3 comprising SEQ ID NO:12; (d) a heavy chain CDR1 comprising SEQ ID NO:121, a heavy chain CDR2 comprising SEQ ID NO:13, a heavy chain CDR3 comprising SEQ ID NO:9, a light chain CDR1 comprising SEQ ID NO:10, a light chain CDR2 comprising SEQ ID NO:11, and a light chain CDR3 comprising SEQ ID NO:12; or (e) a heavy chain CDR1 comprising SEQ ID NO:122, a heavy chain CDR2 comprising SEQ ID NO:130, a heavy chain CDR3 comprising SEQ ID NO:126, a light chain CDR1 comprising SEQ ID NO:127, a light chain CDR2 comprising SEQ ID NO:128, and a light chain CDR3 comprising SEQ ID NO:129.

In certain embodiments, a C3-binding agent (e.g., an antibody) comprises (a) a heavy chain CDR1 comprising SEQ ID NO:7, a heavy chain CDR2 comprising SEQ ID NO:14, SEQ ID NO:15, SEQ ID NO:16, or SEQ ID NO:17, a heavy chain CDR3 comprising SEQ ID NO:9, a light chain CDR1 comprising SEQ ID NO:10, a light chain CDR2 comprising SEQ ID NO:11, and a light chain CDR3 comprising SEQ ID NO:12; (b) a heavy chain CDR1 comprising SEQ ID NO:120, a heavy chain CDR2 comprising SEQ ID NO:131, SEQ ID NO:134, SEQ ID NO:137, or SEQ ID NO:140, a heavy chain CDR3 comprising SEQ ID NO:9, a light chain CDR1 comprising SEQ ID NO:10, a light chain CDR2 comprising SEQ ID NO:11, and a light chain CDR3 comprising SEQ ID NO:12 n; (c) a heavy chain CDR1 comprising SEQ ID NO:7, a heavy chain CDR2 comprising SEQ ID NO:132, SEQ ID NO:135, SEQ ID NO:138, or SEQ ID NO:141, a heavy chain CDR3 comprising SEQ ID NO:9, a light chain CDR1 comprising SEQ ID NO:10, a light chain CDR2 comprising SEQ ID NO:11, and a light chain CDR3 comprising SEQ ID NO:12; (d) a heavy chain CDR1 comprising SEQ ID NO:121, a heavy chain CDR2 comprising SEQ ID NO:14, SEQ ID NO:15, SEQ ID NO:16, or SEQ ID NO:17, a heavy chain CDR3 comprising SEQ ID NO:9, a light chain CDR1 comprising SEQ ID NO:10, a light chain CDR2 comprising SEQ ID NO:11, and a light chain CDR3 comprising SEQ ID NO:12; or (e) a heavy chain CDR1 comprising SEQ ID NO:122, a heavy chain CDR2 comprising SEQ ID NO:133, SEQ ID NO:136, SEQ ID NO:139, or SEQ ID NO:142, a heavy chain CDR3 comprising SEQ ID NO:126, a light chain CDR1 comprising SEQ ID NO:127, a light chain CDR2 comprising SEQ ID NO:128, and a light chain CDR3 comprising SEQ ID NO:129.

In some embodiments, a C3-binding agent (e.g., an antibody) comprises: (a) a heavy chain variable region comprising a heavy chain CDR1 comprising GYTFTDFYMD (SEQ ID NO:7), a heavy chain CDR2 comprising YIYPHNGGTTYNQNFTG (SEQ ID NO:8), YIYPHNGGTTYNQQFTG (SEQ ID NO:13), YIYPHNAGTTYNQQFTG (SEQ ID NO:14), YIYPHNTGTTYNQQFTG (SEQ ID NO:15), YIYPHEGGTTYNQQFTG (SEQ ID NO:16), or YIYPHQGGTTYNQQFTG (SEQ ID NO:17), and a heavy chain CDR3 comprising RGGFDFDY (SEQ ID NO:9); and/or (b) a light chain variable region comprising a light chain CDR1 comprising KASENVDTYVS (SEQ ID NO:10), a light chain CDR2 comprising GASNRYT (SEQ ID NO:11), and a light chain CDR3 comprising GQSHSYPLT (SEQ ID NO:12).

In some embodiments, a C3-binding agent comprises (a) a heavy chain CDR1 comprising GYTFTDFYMD (SEQ ID NO:7), a heavy chain CDR2 comprising YIYPHNGGTTYNQNFTG (SEQ ID NO:8), and a heavy chain CDR3 comprising RGGFDFDY (SEQ ID NO:9), and/or (b) a light chain CDR1 comprising KASENVDTYVS (SEQ ID NO:10), a light chain CDR2 comprising GASNRYT (SEQ ID NO:11), and a light chain CDR3 comprising GQSHSYPLT (SEQ ID NO:12). In some embodiments, a C3-binding agent comprises a heavy chain CDR1 comprising GYTFTDFYMD (SEQ ID NO:7), a heavy chain CDR2 comprising YIYPHNGGTTYNQNFTG (SEQ ID NO:8), and a heavy chain CDR3 comprising RGGFDFDY (SEQ ID NO:9). In some embodiments, a C3-binding agent comprises a light chain CDR1 comprising KASENVDTYVS (SEQ ID NO:10), a light chain CDR2 comprising GASNRYT (SEQ ID NO:11), and a light chain CDR3 comprising GQSHSYPLT (SEQ ID NO:12). In some embodiments, a C3-binding agent comprises (a) a heavy chain CDR1 comprising GYTFTDFYMD (SEQ ID NO:7), a heavy chain CDR2 comprising YIYPHNGGTTYNQNFTG (SEQ ID NO:8), and a heavy chain CDR3 comprising RGGFDFDY (SEQ ID NO:9), and (b) a light chain CDR1 comprising KASENVDTYVS (SEQ ID NO:10), a light chain CDR2 comprising GASNRYT (SEQ ID NO:11), and a light chain CDR3 comprising GQSHSYPLT (SEQ ID NO:12).

In some embodiments, a C3-binding agent comprises (a) a heavy chain CDR1 comprising GYTFTDFYMD (SEQ ID NO:7), a heavy chain CDR2 comprising YIYPHNGGTTYNQQFTG (SEQ ID NO:13), and a heavy chain CDR3 comprising RGGFDFDY (SEQ ID NO:9), and/or (b) a light chain CDR1 comprising KASENVDTYVS (SEQ ID NO:10), a light chain CDR2 comprising GASNRYT (SEQ ID NO:11), and a light chain CDR3 comprising GQSHSYPLT (SEQ ID NO:12). In some embodiments, a C3-binding agent (e.g., an antibody) comprises a heavy chain CDR1 comprising GYTFTDFYMD (SEQ ID NO:7), a heavy chain CDR2 comprising YIYPHNGGTTYNQQFTG (SEQ ID NO:13), and a heavy chain CDR3 comprising RGGFDFDY (SEQ ID NO:9). In some embodiments, a C3-binding agent comprises (a) a heavy chain CDR1 comprising GYTFTDFYMD (SEQ ID NO:7), a heavy chain CDR2 comprising YIYPHNGGTTYNQQFTG (SEQ ID NO:13), and a heavy chain CDR3 comprising RGGFDFDY (SEQ ID NO:9), and (b) a light chain CDR1 comprising KASENVDTYVS (SEQ ID NO:10), a light chain CDR2 comprising GASNRYT (SEQ ID NO:11), and a light chain CDR3 comprising GQSHSYPLT (SEQ ID NO:12).

In some embodiments, a C3-binding agent is a variant of an agent described herein. In some embodiments, a C3-binding agent (e.g., an antibody) comprises (a) a heavy chain CDR1 comprising GYTFTDFYMD (SEQ ID NO:7) or a variant thereof comprising 1, 2, 3, or 4 amino acid substitutions; a heavy chain CDR2 comprising YIYPHNGGTTYNQNFTG (SEQ ID NO:8) or YIYPHNGGTTYNQQFTG (SEQ ID NO:13), or a variant thereof comprising 1, 2, 3, or 4 amino acid substitutions; a heavy chain CDR3 comprising RGGFDFDY (SEQ ID NO:9), or a variant thereof comprising 1, 2, 3, or 4 amino acid substitutions; a light chain CDR1 comprising KASENVDTYVS (SEQ ID NO:10), or a variant thereof comprising 1, 2, 3, or 4 amino acid substitutions; a light chain CDR2 comprising GASNRYT (SEQ ID NO:11), or a variant thereof comprising 1, 2, 3, or 4 amino acid substitutions; and a light chain CDR3 comprising GQSHSYPLT (SEQ ID NO:12), or a variant thereof comprising 1, 2, 3, or 4 amino acid substitutions. In some embodiments, the amino acid substitutions are conservative substitutions. In some embodiments, a CDR comprises one conservative amino acid substitution. In some embodiments, a CDR comprises two conservative amino acid substitutions. In some embodiments, a CDR comprises three conservative amino acid substitutions. In some embodiments, a CDR comprises four conservative amino acid substitutions. In some embodiments, the CDR is a heavy chain CDR1. In some embodiments, the CDR is a heavy chain CDR2. In some embodiment, the CDR is a heavy chain CDR3. In some embodiments, the CDR is a light chain CDR1. In some embodiments, the CDR is a light chain CDR2. In some embodiments, the CDR is a light chain CDR3. In some embodiments, the substitutions are made as part of a humanization process. In some embodiments, the substitutions are made as part of a germline humanization process. In some embodiments, the substitutions are made as part of an affinity maturation process. In some embodiments, the substitutions are made as part of an optimization process.

In some embodiments, a C3-binding agent (e.g., an antibody) comprises one or more heavy chain or light chain CDRs that have been modified to reduce deamidation within the CDR sequence. Deamidation is a chemical reaction in which an amide functional group in the side chain of the amino acids asparagine (N) or glutamine (Q) is removed or converted to another functional group. Generally, asparagine is converted to aspartic acid or isoaspartic acid and glutamine is converted to glutamic acid or polyglutamic acid. In some situations, deamidation may change the structure, function, and/or stability of a polypeptide, potentially resulting in decreased biological activity.

In some embodiments, a C3-binding agent (e.g., an antibody) comprises (a) a heavy chain CDR1 comprising GYTFTDFYMD (SEQ ID NO:7), a heavy chain CDR2 comprising YIYPHNAGTTYNQQFTG (SEQ ID NO:14), YIYPHNTGTTYNQQFTG (SEQ ID NO:15), YIYPHEGGTTYNQQFTG (SEQ ID NO:16), or YIYPHQGGTTYNQQFTG (SEQ ID NO:17), and a heavy chain CDR3 comprising RGGFDFDY (SEQ ID NO:9), and/or (b) a light chain CDR1 comprising KASENVDTYVS (SEQ ID NO:10), a light chain CDR2 comprising GASNRYT (SEQ ID NO:11), and a light chain CDR3 comprising GQSHSYPLT (SEQ ID NO:12). In some embodiments, a C3-binding agent comprises (a) a heavy chain CDR1 comprising GYTFTDFYMD (SEQ ID NO:7), a heavy chain CDR2 comprising YIYPHNAGTTYNQQFTG (SEQ ID NO:14), and a heavy chain CDR3 comprising RGGFDFDY (SEQ ID NO:9). In some embodiments, a C3-binding agent comprises (a) a heavy chain CDR1 comprising GYTFTDFYMD (SEQ ID NO:7), a heavy chain CDR2 comprising YIYPHNAGTTYNQQFTG (SEQ ID NO:14), and a heavy chain CDR3 comprising RGGFDFDY (SEQ ID NO:9), and (b) a light chain CDR1 comprising KASENVDTYVS (SEQ ID NO:10), a light chain CDR2 comprising GASNRYT (SEQ ID NO:11), and a light chain CDR3 comprising GQSHSYPLT (SEQ ID NO:12). In some embodiments, a C3-binding agent comprises (a) a heavy chain CDR1 comprising GYTFTDFYMD (SEQ ID NO:7), a heavy chain CDR2 comprising YIYPHNTGTTYNQQFTG (SEQ ID NO:15), and a heavy chain CDR3 comprising RGGFDFDY (SEQ ID NO:9). In some embodiments, a C3-binding agent comprises (a) a heavy chain CDR1 comprising GYTFTDFYMD (SEQ ID NO:7), a heavy chain CDR2 comprising YIYPHNTGTTYNQQFTG (SEQ ID NO:15), and a heavy chain CDR3 comprising RGGFDFDY (SEQ ID NO:9), and (b) a light chain CDR1 comprising KASENVDTYVS (SEQ ID NO:10), a light chain CDR2 comprising GASNRYT (SEQ ID NO:11), and a light chain CDR3 comprising GQSHSYPLT (SEQ ID NO:12). In some embodiments, a C3-binding agent comprises (a) a heavy chain CDR1 comprising GYTFTDFYMD (SEQ ID NO:7), a heavy chain CDR2 comprising YIYPHEGGTTYNQQFTG (SEQ ID NO:16), and a heavy chain CDR3 comprising RGGFDFDY (SEQ ID NO:9). In some embodiments, a C3-binding agent comprises (a) a heavy chain CDR1 comprising GYTFTDFYMD (SEQ ID NO:7), a heavy chain CDR2 comprising YIYPHEGGTTYNQQFTG (SEQ ID NO:16), and a heavy chain CDR3 comprising RGGFDFDY (SEQ ID NO:9), and (b) a light chain CDR1 comprising KASENVDTYVS (SEQ ID NO:10), a light chain CDR2 comprising GASNRYT (SEQ ID NO:11), and a light chain CDR3 comprising GQSHSYPLT (SEQ ID NO:12). In some embodiments, a C3-binding agent comprises (a) a heavy chain CDR1 comprising GYTFTDFYMD (SEQ ID NO:7), a heavy chain CDR2 comprising YIYPHQGGTTYNQQFTG (SEQ ID NO:17), and a heavy chain CDR3 comprising RGGFDFDY (SEQ ID NO:9). In some embodiments, a C3-binding agent comprises (a) a heavy chain CDR1 comprising GYTFTDFYMD (SEQ ID NO:7), a heavy chain CDR2 comprising YIYPHQGGTTYNQQFTG (SEQ ID NO:17), and a heavy chain CDR3 comprising RGGFDFDY (SEQ ID NO:9), and (b) a light chain CDR1 comprising KASENVDTYVS (SEQ ID NO:10), a light chain CDR2 comprising GASNRYT (SEQ ID NO:11), and a light chain CDR3 comprising GQSHSYPLT (SEQ ID NO:12).

In certain embodiments, a C3-binding agent comprises a heavy chain variable region comprising heavy chain CDRs 1, 2, and 3, and a light chain variable region comprising light chain CDRs 1, 2, and 3, wherein heavy chain CDR1 comprises GYTFTDFYMD (SEQ ID NO:7), heavy chain CDR2 comprises YIYPHNGGTTYNQNFTG (SEQ ID NO:8), heavy chain CDR3 comprises RGGFDFDY (SEQ ID NO:9), light chain CDR1 comprises KASENVDTYVS (SEQ ID NO:10), light chain CDR2 comprises GASNRYT (SEQ ID NO:11), and light chain CDR3 comprises GQSHSYPLT (SEQ ID NO:12). In certain embodiments, a C3-binding agent comprises a heavy chain variable region comprising heavy chain CDRs 1, 2, and 3, and a light chain variable region comprising light chain CDRs 1, 2, and 3, wherein heavy chain CDR1 comprises GYTFTDFYMD (SEQ ID NO:7), heavy chain CDR2 comprises YIYPHNGGTTYNQQFTG (SEQ ID NO:13), heavy chain CDR3 comprises RGGFDFDY (SEQ ID NO:9), light chain CDR1 comprises KASENVDTYVS (SEQ ID NO:10), light chain CDR2 comprises GASNRYT (SEQ ID NO:11), and light chain CDR3 comprises GQSHSYPLT (SEQ ID NO:12). In certain embodiments, a C3-binding agent comprises a heavy chain variable region comprising heavy chain CDRs 1, 2, and 3, and a light chain variable region comprising light chain CDRs 1, 2, and 3, wherein heavy chain CDR1 comprises GYTFTDFYMD (SEQ ID NO: 7), heavy chain CDR2 comprises YIYPHNAGTTYNQQFTG (SEQ ID NO:14), heavy chain CDR3 comprises RGGFDFDY (SEQ ID NO:9), light chain CDR1 comprises KASENVDTYVS (SEQ ID NO:10), light chain CDR2 comprises GASNRYT (SEQ ID NO:11), and light chain CDR3 comprises GQSHSYPLT (SEQ ID NO:12). In certain embodiments, a C3-binding agent comprises a heavy chain variable region comprising heavy chain CDRs 1, 2, and 3, and a light chain variable region comprising light chain CDRs 1, 2, and 3, wherein heavy chain CDR1 comprises GYTFTDFYMD (SEQ ID NO:7), heavy chain CDR2 comprises YIYPHNTGTTYNQQFTG (SEQ ID NO:15), heavy chain CDR3 comprises RGGFDFDY (SEQ ID NO:9), light chain CDR1 comprises KASENVDTYVS (SEQ ID NO:10), light chain CDR2 comprises GASNRYT (SEQ ID NO:11), and light chain CDR3 comprises GQSHSYPLT (SEQ ID NO:12). In certain embodiments, a C3-binding agent comprises a heavy chain variable region comprising heavy chain CDRs 1, 2, and 3, and a light chain variable region comprising light chain CDRs 1, 2, and 3, wherein heavy chain CDR1 comprises GYTFTDFYMD (SEQ ID NO:7), heavy chain CDR2 comprises YIYPHEGGTTYNQQFTG (SEQ ID NO:16), heavy chain CDR3 comprises RGGFDFDY (SEQ ID NO:9), light chain CDR1 comprises KASENVDTYVS (SEQ ID NO:10), light chain CDR2 comprises GASNRYT (SEQ ID NO:11), and light chain CDR3 comprises GQSHSYPLT (SEQ ID NO:12). In certain embodiments, a C3-binding agent comprises a heavy chain variable region comprising heavy chain CDRs 1, 2, and 3, and a light chain variable region comprising light chain CDRs 1, 2, and 3, wherein heavy chain CDR1 comprises GYTFTDFYMD (SEQ ID NO:7), heavy chain CDR2 comprises YIYPHQGGTTYNQQFTG (SEQ ID NO:17), heavy chain CDR3 comprises RGGFDFDY (SEQ ID NO:9), light chain CDR1 comprises KASENVDTYVS (SEQ ID NO:10), light chain CDR2 comprises GASNRYT (SEQ ID NO:11), and light chain CDR3 comprises GQSHSYPLT (SEQ ID NO:12).

In some embodiments, a C3-binding agent (e.g., an antibody) comprises a heavy chain variable region having at least about 80% sequence identity to SEQ ID NO:18, SEQ ID NO:20, SEQ ID NO:21, SEQ ID NO:22, SEQ ID NO:23, or SEQ ID NO:24; and/or a light chain variable region having at least 80% sequence identity to SEQ ID NO:19 or SEQ ID NO:25. In some embodiments, a C3-binding agent (e.g., an antibody) comprises a heavy chain variable region having at least about 85%, at least about 90%, at least about 95%, at least about 97%, or at least about 99% sequence identity to SEQ ID NO:18. In some embodiments, a C3-binding agent (e.g., an antibody) comprises a light chain variable region having at least about 85%, at least about 90%, at least about 95%, at least about 97%, or at least about 99% sequence identity to SEQ ID NO:19. In some embodiments, a C3-binding agent (e.g., an antibody) comprises a heavy chain variable region having at least about 85%, at least about 90%, at least about 95%, at least about 97%, or at least about 99% sequence identity to SEQ ID NO:20. In some embodiments, a C3-binding agent (e.g., an antibody) comprises a heavy chain variable region having at least about 85%, at least about 90%, at least about 95%, at least about 97%, or at least about 99% sequence identity to SEQ ID NO:21. In some embodiments, a C3-binding agent (e.g., an antibody) comprises a heavy chain variable region having at least about 85%, at least about 90%, at least about 95%, at least about 97%, or at least about 99% sequence identity to SEQ ID NO:22. In some embodiments, a C3-binding agent (e.g., an antibody) comprises a heavy chain variable region having at least about 85%, at least about 90%, at least about 95%, at least about 97%, or at least about 99% sequence identity to SEQ ID NO:23. In some embodiments, a C3-binding agent (e.g., an antibody) comprises a heavy chain variable region having at least about 85%, at least about 90%, at least about 95%, at least about 97%, or at least about 99% sequence identity to SEQ ID NO:24. In some embodiments, a C3-binding agent (e.g., an antibody) comprises a light chain variable region having at least about 85%, at least about 90%, at least about 95%, at least about 97%, or at least about 99% sequence identity to SEQ ID NO:25.

In some embodiments, a C3-binding agent (e.g., an antibody) comprises a heavy chain variable region having at least about 80% sequence identity to SEQ ID NO:18 and/or a light chain variable region having at least about 80% sequence identity to SEQ ID NO:19. In some embodiments, a C3-binding agent (e.g., an antibody) comprises a heavy chain variable region having at least about 80% sequence identity to SEQ ID NO:18 and a light chain variable region having at least about 80% sequence identity to SEQ ID NO:19. In some embodiments, a C3-binding agent (e.g., an antibody) comprises a heavy chain variable region having at least about 90% sequence identity to SEQ ID NO:18 and/or a light chain variable region having at least about 90% sequence identity to SEQ ID NO:19. In some embodiments, a C3-binding agent (e.g., an antibody) comprises a heavy chain variable region having at least about 90% sequence identity to SEQ ID NO:18 and a light chain variable region having at least about 90% sequence identity to SEQ ID NO:19. In some embodiments, a C3-binding agent (e.g., an antibody) comprises a heavy chain variable region having at least about 95% sequence identity to SEQ ID NO:18 and/or a light chain variable region having at least about 95% sequence identity to SEQ ID NO:19. In some embodiments, a C3-binding agent (e.g., an antibody) comprises a heavy chain variable region having at least about 95% sequence identity to SEQ ID NO:18 and a light chain variable region having at least about 95% sequence identity to SEQ ID NO:19.

In some embodiments, a C3-binding agent (e.g., an antibody) comprises a heavy chain variable region having at least about 90% sequence identity to SEQ ID NO:20, SEQ ID NO:21, SEQ ID NO:22, SEQ ID NO:23, or SEQ ID NO:24; and/or a light chain variable region having at least about 90% sequence identity to SEQ ID NO:25. In some embodiments, a C3-binding agent (e.g., an antibody) comprises a heavy chain variable region having at least about 90% sequence identity to SEQ ID NO:20, SEQ ID NO:21, SEQ ID NO:22, SEQ ID NO:23, or SEQ ID NO:24; and a light chain variable region having at least about 90% sequence identity to SEQ ID NO:25. In some embodiments, a C3-binding agent (e.g., an antibody) comprises a heavy chain variable region having at least about 95% sequence identity to SEQ ID NO:20, SEQ ID NO:21, SEQ ID NO:22, SEQ ID NO:23, or SEQ ID NO:24; and/or a light chain variable region having at least about 95% sequence identity to SEQ ID NO:25. In some embodiments, a C3-binding agent (e.g., an antibody) comprises a heavy chain variable region having at least about 95% sequence identity to SEQ ID NO:20, SEQ ID NO:21, SEQ ID NO:22, SEQ ID NO:23, or SEQ ID NO:24; and a light chain variable region having at least about 95% sequence identity to SEQ ID NO:25. In some embodiments, a C3-binding agent comprises a heavy chain variable region having at least about 95% sequence identity to SEQ ID NO:20 and a light chain variable region having at least about 95% sequence identity to SEQ ID NO:25. In some embodiments, a C3-binding agent comprises a heavy chain variable region having at least about 95% sequence identity to SEQ ID NO:21 and a light chain variable region having at least about 95% sequence identity to SEQ ID NO:25. In some embodiments, a C3-binding agent comprises a heavy chain variable region having at least about 95% sequence identity to SEQ ID NO:22 and a light chain variable region having at least about 95% sequence identity to SEQ ID NO:25. In some embodiments, a C3-binding agent comprises a heavy chain variable region having at least about 95% sequence identity to SEQ ID NO:23 and a light chain variable region having at least about 95% sequence identity to SEQ ID NO:25. In some embodiments, a C3-binding agent comprises a heavy chain variable region having at least about 95% sequence identity to SEQ ID NO:24; and a light chain variable region having at least about 95% sequence identity to SEQ ID NO:25.

In some embodiments, a C3-binding agent (e.g., an antibody) comprises a heavy chain variable region comprising SEQ ID NO:18. In some embodiments, a C3-binding agent comprises a light chain variable region comprising SEQ ID NO:19. In some embodiments, a C3-binding agent comprises a heavy chain variable region comprising SEQ ID NO:18 and a light chain variable region comprising SEQ ID NO:19.

In some embodiments, a C3-binding agent (e.g., an antibody) comprises a heavy chain variable region comprising SEQ ID NO:20, SEQ ID NO:21, SEQ ID NO:22, SEQ ID NO:23, or SEQ ID NO:24; and/or a light chain variable region comprising SEQ ID NO:25. In some embodiments, a C3-binding agent comprises a heavy chain variable region comprising SEQ ID NO:20. In some embodiments, a C3-binding agent comprises a heavy chain variable region comprising SEQ ID NO:21. In some embodiments, a C3-binding agent comprises a heavy chain variable region comprising SEQ ID NO:22. In some embodiments, a C3-binding agent comprises a heavy chain variable region comprising SEQ ID NO:23. In some embodiments, a C3-binding agent (e.g., an antibody) comprises a heavy chain variable region comprising SEQ ID NO:24. In some embodiments, a C3-binding agent comprises a light chain variable region comprising SEQ ID NO:25. In some embodiments, a C3-binding agent comprises a heavy chain variable region comprising SEQ ID NO:20 and a light chain variable region comprising SEQ ID NO:25. In some embodiments, a C3-binding agent comprises a heavy chain variable region comprising SEQ ID NO:21 and a light chain variable region comprising SEQ ID NO:25. In some embodiments, a C3-binding agent comprises a heavy chain variable region comprising SEQ ID NO:22 and a light chain variable region comprising SEQ ID NO:25. In some embodiments, a C3-binding agent comprises a heavy chain variable region comprising SEQ ID NO:23 and a light chain variable region comprising SEQ ID NO:25. In some embodiments, a C3-binding agent comprises a heavy chain variable region comprising SEQ ID NO:24 and a light chain variable region comprising SEQ ID NO:25.

In some embodiments, a C3-binding agent (e.g., an antibody) comprises a CDR1, CDR2, and CDR3 from a heavy chain variable region having the amino acid sequence of SEQ ID NO:18 and a CDR1, CDR2, and CDR3 from a light chain variable region having the amino acid sequence of SEQ ID NO:19. In some embodiments, a C3-binding agent (e.g., an antibody) comprises a CDR1, CDR2, and CDR3 from a heavy chain variable region having the amino acid sequence of SEQ ID NO:20 and a CDR1, CDR2, and CDR3 from a light chain variable region having the amino acid sequence of SEQ ID NO:25. In some embodiments, a C3-binding agent (e.g., an antibody) comprises a CDR1, CDR2, and CDR3 from a heavy chain variable region having the amino acid sequence of SEQ ID NO:21 and a CDR1, CDR2, and CDR3 from a light chain variable region having the amino acid sequence of SEQ ID NO:25. In some embodiments, a C3-binding agent (e.g., an antibody) comprises a CDR1, CDR2, and CDR3 from a heavy chain variable region having the amino acid sequence of SEQ ID NO:22 and a CDR1, CDR2, and CDR3 from a light chain variable region having the amino acid sequence of SEQ ID NO:25. In some embodiments, a C3-binding agent (e.g., an antibody) comprises a CDR1, CDR2, and CDR3 from a heavy chain variable region having the amino acid sequence of SEQ ID NO:23 and a CDR1, CDR2, and CDR3 from a light chain variable region having the amino acid sequence of SEQ ID NO:25. In some embodiments, a C3-binding agent (e.g., an antibody) comprises a CDR1, CDR2, and CDR3 from a heavy chain variable region having the amino acid sequence of SEQ ID NO:24 and a CDR1, CDR2, and CDR3 from a light chain variable region having the amino acid sequence of SEQ ID NO:25.

In certain embodiments, a C3-binding agent (e.g., an antibody) comprises (a) a heavy chain CDR1 comprising SEQ ID NO:38, a heavy chain CDR2 comprising SEQ ID NO:39, a heavy chain CDR3 comprising SEQ ID NO:40, a light chain CDR1 comprising SEQ ID NO:41, a light chain CDR2 comprising SEQ ID NO:42, and a light chain CDR3 comprising SEQ ID NO:43; (b) a heavy chain CDR1 comprising SEQ ID NO:143, a heavy chain CDR2 comprising SEQ ID NO:146, a heavy chain CDR3 comprising SEQ ID NO:40, a light chain CDR1 comprising SEQ ID NO:41, a light chain CDR2 comprising SEQ ID NO:42, and a light chain CDR3 comprising SEQ ID NO:43; (c) a heavy chain CDR1 comprising SEQ ID NO:38, a heavy chain CDR2 comprising SEQ ID NO:147, a heavy chain CDR3 comprising SEQ ID NO:40, a light chain CDR1 comprising SEQ ID NO:41, a light chain CDR2 comprising SEQ ID NO:42, and a light chain CDR3 comprising SEQ ID NO:43; (d) a heavy chain CDR1 comprising SEQ ID NO:144, a heavy chain CDR2 comprising SEQ ID NO:39, a heavy chain CDR3 comprising SEQ ID NO:40, a light chain CDR1 comprising SEQ ID NO:41, a light chain CDR2 comprising SEQ ID NO:42, and a light chain CDR3 comprising SEQ ID NO:43; or (e) a heavy chain CDR1 comprising SEQ ID NO:145, a heavy chain CDR2 comprising SEQ ID NO:149, a heavy chain CDR3 comprising SEQ ID NO:150, a light chain CDR1 comprising SEQ ID NO:151, a light chain CDR2 comprising SEQ ID NO:152, and a light chain CDR3 comprising SEQ ID NO:153.

In some embodiments, a C3-binding agent (e.g., an antibody) comprises (a) a heavy chain CDR1 comprising GYSFTGYNMN (SEQ ID NO:38), a heavy chain CDR2 comprising NINPYYGSTNYNQKFKG (SEQ ID NO:39), and a heavy chain CDR3 comprising GYYGGNYPFAY (SEQ ID NO:40), and/or (b) a light chain CDR1 comprising RASENIYSYLA (SEQ ID NO:41), a light chain CDR2 comprising NAKTLAE (SEQ ID NO:42), and a light chain CDR3 comprising QHYYGTPYT (SEQ ID NO:43). In some embodiments, a C3-binding agent (e.g., an antibody) comprises (a) a heavy chain CDR1 comprising GYSFTGYNMN (SEQ ID NO:38), a heavy chain CDR2 comprising NINPYYGSTNYNQKFKG (SEQ ID NO:39), and a heavy chain CDR3 comprising GYYGGNYPFAY (SEQ ID NO:40), and (b) a light chain CDR1 comprising RASENIYSYLA (SEQ ID NO:41), a light chain CDR2 comprising NAKTLAE (SEQ ID NO:42), and a light chain CDR3 comprising QHYYGTPYT (SEQ ID NO:43).

In some embodiments, a C3-binding agent (e.g., an antibody) comprises (a) a heavy chain variable region comprising a heavy chain CDR1 comprising GYSFTGYNMN (SEQ ID NO:38), a heavy chain CDR2 comprising NINPYYGSTNYNQKFKG (SEQ ID NO:39), and a heavy chain CDR3 comprising GYYGGNYPFAY (SEQ ID NO:40), and/or (b) a light chain variable region comprising a light chain CDR1 comprising RASENIYSYLA (SEQ ID NO:41), a light chain CDR2 comprising NAKTLAE (SEQ ID NO:42), and a light chain CDR3 comprising QHYYGTPYT (SEQ ID NO:43). In some embodiments, a C3-binding agent (e.g., an antibody) comprises (a) a heavy chain variable region comprising a heavy chain CDR1 comprising GYSFTGYNMN (SEQ ID NO:38), a heavy chain CDR2 comprising NINPYYGSTNYNQKFKG (SEQ ID NO:39), and a heavy chain CDR3 comprising GYYGGNYPFAY (SEQ ID NO:40), and (b) a light chain variable region comprising a light chain CDR1 comprising RASENIYSYLA (SEQ ID NO:41), a light chain CDR2 comprising NAKTLAE (SEQ ID NO:42), and a light chain CDR3 comprising QHYYGTPYT (SEQ ID NO:43).

In certain embodiments, a C3-binding agent comprises heavy chain CDRs 1, 2, and 3, of a heavy chain variable region comprising the amino acid sequence set forth in SEQ ID NO:91. In certain embodiments, a C3-binding agent comprises light chain CDRs 1, 2, and 3 of a light chain variable region comprising the amino acid sequence set forth in SEQ ID NO:92. In certain embodiments, a C3-binding agent comprises heavy chain CDRs 1, 2, and 3 of a heavy chain variable region comprising the amino acid sequence set forth in SEQ ID NO:91, and light chain CDRs 1, 2, and 3, of a light chain variable region comprising the amino acid sequence set forth in SEQ ID NO:92.

In some embodiments, a C3-binding agent (e.g., an antibody) comprises a heavy chain variable region having at least about 80%, about 85%, about 90%, or about 95% sequence identity to SEQ ID NO:91 and/or a light chain variable region having at least about 80%, about 85%, about 90%, or about 95% sequence identity to SEQ ID NO:92. In some embodiments, a C3-binding agent (e.g., an antibody) comprises a heavy chain variable region comprising SEQ ID NO:91 and/or a light chain variable region comprising SEQ ID NO:92. In some embodiments, a C3-binding agent (e.g., an antibody) comprises a heavy chain variable region of SEQ ID NO:91 and a light chain variable region of SEQ ID NO:92.

In certain embodiments, a C3-binding agent (e.g., an antibody) comprises (a) a heavy chain CDR1 comprising SEQ ID NO:38, a heavy chain CDR2 comprising SEQ ID NO:44, a heavy chain CDR3 comprising SEQ ID NO:45, a light chain CDR1 comprising SEQ ID NO:46, a light chain CDR2 comprising SEQ ID NO:47, and a light chain CDR3 comprising SEQ ID NO:48; (b) a heavy chain CDR1 comprising SEQ ID NO:143, a heavy chain CDR2 comprising SEQ ID NO:154, a heavy chain CDR3 comprising SEQ ID NO:45, a light chain CDR1 comprising SEQ ID NO:46, a light chain CDR2 comprising SEQ ID NO:47, and a light chain CDR3 comprising SEQ ID NO:48; (c) a heavy chain CDR1 comprising SEQ ID NO:38, a heavy chain CDR2 comprising SEQ ID NO:155, a heavy chain CDR3 comprising SEQ ID NO:45, a light chain CDR1 comprising SEQ ID NO:46, a light chain CDR2 comprising SEQ ID NO:47, and a light chain CDR3 comprising SEQ ID NO:48; (d) a heavy chain CDR1 comprising SEQ ID NO:144, a heavy chain CDR2 comprising SEQ ID NO:44, a heavy chain CDR3 comprising SEQ ID NO:45, a light chain CDR1 comprising SEQ ID NO:46, a light chain CDR2 comprising SEQ ID NO:47, and a light chain CDR3 comprising SEQ ID NO:48; or (e) a heavy chain CDR1 comprising SEQ ID NO:145, a heavy chain CDR2 comprising SEQ ID NO:156, a heavy chain CDR3 comprising SEQ ID NO:157, a light chain CDR1 comprising SEQ ID NO:158, a light chain CDR2 comprising SEQ ID NO:159, and a light chain CDR3 comprising SEQ ID NO:160.

In some embodiments, a C3-binding agent (e.g., an antibody) comprises (a) a heavy chain CDR1 comprising GYSFTGYNMN (SEQ ID NO:38), a heavy chain CDR2 comprising NINPYYDSTSYNQKFKG (SEQ ID NO:44), and a heavy chain CDR3 comprising ENYDFVGFAY (SEQ ID NO:45), and/or (b) a light chain CDR1 comprising RASSSVSYMH (SEQ ID NO:46), a light chain CDR2 comprising VTSNLAS (SEQ ID NO:47), and a light chain CDR3 comprising QQWSTNPLT (SEQ ID NO:48). In some embodiments, a C3-binding agent (e.g., an antibody) comprises (a) a heavy chain CDR1 comprising GYSFTGYNMN (SEQ ID NO:38), a heavy chain CDR2 comprising NINPYYDSTSYNQKFKG (SEQ ID NO:44), and a heavy chain CDR3 comprising ENYDFVGFAY (SEQ ID NO:45), and (b) a light chain CDR1 comprising RASSSVSYMH (SEQ ID NO:46), a light chain CDR2 comprising VTSNLAS (SEQ ID NO:47), and a light chain CDR3 comprising QQWSTNPLT (SEQ ID NO:48).

In some embodiments, a C3-binding agent (e.g., an antibody) comprises (a) a heavy chain variable region comprising a heavy chain CDR1 comprising GYSFTGYNMN (SEQ ID NO:38), a heavy chain CDR2 comprising NINPYYDSTSYNQKFKG (SEQ ID NO:44), and a heavy chain CDR3 comprising ENYDFVGFAY (SEQ ID NO:45), and/or (b) a light chain variable region comprising a light chain CDR1 comprising RASSSVSYMH (SEQ ID NO:46), a light chain CDR2 comprising VTSNLAS (SEQ ID NO:47), and a light chain CDR3 comprising QQWSTNPLT (SEQ ID NO:48). In some embodiments, a C3-binding agent (e.g., an antibody) comprises (a) a heavy chain variable region comprising a heavy chain CDR1 comprising GYSFTGYNMN (SEQ ID NO:38), a heavy chain CDR2 comprising NINPYYDSTSYNQKFKG (SEQ ID NO:44), and a heavy chain CDR3 comprising ENYDFVGFAY (SEQ ID NO:45), and (b) a light chain variable region comprising a light chain CDR1 comprising RASSSVSYMH (SEQ ID NO:46), a light chain CDR2 comprising VTSNLAS (SEQ ID NO:47), and a light chain CDR3 comprising QQWSTNPLT (SEQ ID NO:48).

In certain embodiments, a C3-binding agent comprises heavy chain CDRs 1, 2, and 3 of a heavy chain variable region comprising the amino acid sequence set forth in SEQ ID NO:93. In certain embodiments, a C3-binding agent comprises light chain CDRs 1, 2, and 3 of a light chain variable region comprising the amino acid sequence set forth in SEQ ID NO:94. In certain embodiments, a C3-binding agent comprises heavy chain CDRs 1, 2, and 3 of a heavy chain variable region comprising the amino acid sequence set forth in SEQ ID NO:93, and light chain CDRs 1, 2, and 3 of a light chain variable region comprising the amino acid sequence set forth in SEQ ID NO:94.

In some embodiments, a C3-binding agent (e.g., an antibody) comprises a heavy chain variable region having at least about 80%, about 85%, about 90%, or about 95% sequence identity to SEQ ID NO:93 and/or a light chain variable region having at least about 80%, about 85%, about 90%, or about 95% sequence identity to SEQ ID NO:94. In some embodiments, a C3-binding agent (e.g., an antibody) comprises a heavy chain variable region comprising SEQ ID NO:93 and/or a light chain variable region comprising SEQ ID NO:94. In some embodiments, a C3-binding agent (e.g., an antibody) comprises a heavy chain variable region of SEQ ID NO:93 and a light chain variable region of SEQ ID NO:94.

In certain embodiments, a C3-binding agent (e.g., an antibody) comprises (a) a heavy chain CDR1 comprising SEQ ID NO:49, a heavy chain CDR2 comprising SEQ ID NO:50, a heavy chain CDR3 comprising SEQ ID NO:51, a light chain CDR1 comprising SEQ ID NO:52, a light chain CDR2 comprising SEQ ID NO:53, and a light chain CDR3 comprising SEQ ID NO:54; (b) a heavy chain CDR1 comprising SEQ ID NO:143, a heavy chain CDR2 comprising SEQ ID NO:163, a heavy chain CDR3 comprising SEQ ID NO:51, a light chain CDR1 comprising SEQ ID NO:52, a light chain CDR2 comprising SEQ ID NO:53, and a light chain CDR3 comprising SEQ ID NO:54; (c) a heavy chain CDR1 comprising SEQ ID NO:49, a heavy chain CDR2 comprising SEQ ID NO:164, a heavy chain CDR3 comprising SEQ ID NO:51, a light chain CDR1 comprising SEQ ID NO:52, a light chain CDR2 comprising SEQ ID NO:53, and a light chain CDR3 comprising SEQ ID NO:54; (d) a heavy chain CDR1 comprising SEQ ID NO:161, a heavy chain CDR2 comprising SEQ ID NO:50, a heavy chain CDR3 comprising SEQ ID NO:51, a light chain CDR1 comprising SEQ ID NO:52, a light chain CDR2 comprising SEQ ID NO:53, and a light chain CDR3 comprising SEQ ID NO:54; or (e) a heavy chain CDR1 comprising SEQ ID NO:162, a heavy chain CDR2 comprising SEQ ID NO:165, a heavy chain CDR3 comprising SEQ ID NO:166, a light chain CDR1 comprising SEQ ID NO:167, a light chain CDR2 comprising SEQ ID NO:168, and a light chain CDR3 comprising SEQ ID NO:169.

In some embodiments, a C3-binding agent (e.g., an antibody) comprises (a) a heavy chain CDR1 comprising GYSFTGYNMH (SEQ ID NO:49), a heavy chain CDR2 comprising NINPYYGTTNSNQKFED (SEQ ID NO:50), and a heavy chain CDR3 comprising GIYYYGTGYPYFDF (SEQ ID NO:51), and/or (b) a light chain CDR1 comprising RASQDINNYLN (SEQ ID NO:52), a light chain CDR2 comprising YTSRLHS (SEQ ID NO:53), and a light chain CDR3 comprising QQGITLPWT (SEQ ID NO:54). In some embodiments, a C3-binding agent (e.g., an antibody) comprises (a) a heavy chain CDR1 comprising GYSFTGYNMH (SEQ ID NO:49), a heavy chain CDR2 comprising NINPYYGTTNSNQKFED (SEQ ID NO:50), and a heavy chain CDR3 comprising GIYYYGTGYPYFDF (SEQ ID NO:51), and (b) a light chain CDR1 comprising RASQDINNYLN (SEQ ID NO:52), a light chain CDR2 comprising YTSRLHS (SEQ ID NO:53), and a light chain CDR3 comprising QQGITLPWT (SEQ ID NO:54).

In some embodiments, a C3-binding agent (e.g., an antibody) comprises (a) a heavy chain variable region comprising a heavy chain CDR1 comprising GYSFTGYNMH (SEQ ID NO:49), a heavy chain CDR2 comprising NINPYYGTTNSNQKFED (SEQ ID NO:50), and a heavy chain CDR3 comprising GIYYYGTGYPYFDF (SEQ ID NO:51), and/or (b) a light chain variable region comprising a light chain CDR1 comprising RASQDINNYLN (SEQ ID NO:52), a light chain CDR2 comprising YTSRLHS (SEQ ID NO:53), and a light chain CDR3 comprising QQGITLPWT (SEQ ID NO:54). In some embodiments, a C3-binding agent (e.g., an antibody) comprises (a) a heavy chain variable region comprising a heavy chain CDR1 comprising GYSFTGYNMH (SEQ ID NO:49), a heavy chain CDR2 comprising NINPYYGTTNSNQKFED (SEQ ID NO:50), and a heavy chain CDR3 comprising GIYYYGTGYPYFDF (SEQ ID NO:51), and (b) a light chain variable region comprising a light chain CDR1 comprising RASQDINNYLN (SEQ ID NO:52), a light chain CDR2 comprising YTSRLHS (SEQ ID NO:53), and a light chain CDR3 comprising QQGITLPWT (SEQ ID NO:54).

In certain embodiments, a C3-binding agent comprises heavy chain CDRs 1, 2, and 3 of a heavy chain variable region comprising the amino acid sequence set forth in SEQ ID NO:95. In certain embodiments, a C3-binding agent comprises light chain CDRs 1, 2, and 3 of a light chain variable region comprising the amino acid sequence set forth in SEQ ID NO:96. In certain embodiments, a C3-binding agent comprises heavy chain CDRs 1, 2, and 3 of a heavy chain variable region comprising the amino acid sequence set forth in SEQ ID NO:95, and light chain CDRs 1, 2, and 3 of a light chain variable region comprising the amino acid sequence set forth in SEQ ID NO:96.

In some embodiments, a C3-binding agent (e.g., an antibody) comprises a heavy chain variable region having at least about 80%, about 85%, about 90%, or about 95% sequence identity to SEQ ID NO:95 and/or a light chain variable region having at least about 80%, about 85%, about 90%, or about 95% sequence identity to SEQ ID NO:96. In some embodiments, a C3-binding agent (e.g., an antibody) comprises a heavy chain variable region comprising SEQ ID NO:95 and/or a light chain variable region comprising SEQ ID NO:96. In some embodiments, a C3-binding agent (e.g., an antibody) comprises a heavy chain variable region of SEQ ID NO:95 and a light chain variable region of SEQ ID NO:96.

In certain embodiments, a C3-binding agent (e.g., an antibody) comprises (a) a heavy chain CDR1 comprising SEQ ID NO:55, a heavy chain CDR2 comprising SEQ ID NO:56, a heavy chain CDR3 comprising SEQ ID NO:57, a light chain CDR1 comprising SEQ ID NO:58, a light chain CDR2 comprising SEQ ID NO:59, and a light chain CDR3 comprising SEQ ID NO:60; (b) a heavy chain CDR1 comprising SEQ ID NO:170, a heavy chain CDR2 comprising SEQ ID NO:173, a heavy chain CDR3 comprising SEQ ID NO:57, a light chain CDR1 comprising SEQ ID NO:58, a light chain CDR2 comprising SEQ ID NO:59, and a light chain CDR3 comprising SEQ ID NO:60; (c) a heavy chain CDR1 comprising SEQ ID NO:55, a heavy chain CDR2 comprising SEQ ID NO:174, a heavy chain CDR3 comprising SEQ ID NO:57, a light chain CDR1 comprising SEQ ID NO:58, a light chain CDR2 comprising SEQ ID NO:59, and a light chain CDR3 comprising SEQ ID NO:60; (d) a heavy chain CDR1 comprising SEQ ID NO:171, a heavy chain CDR2 comprising SEQ ID NO:56, a heavy chain CDR3 comprising SEQ ID NO:57, a light chain CDR1 comprising SEQ ID NO:58, a light chain CDR2 comprising SEQ ID NO:59, and a light chain CDR3 comprising SEQ ID NO:60; or (e) a heavy chain CDR1 comprising SEQ ID NO:172, a heavy chain CDR2 comprising SEQ ID NO:175, a heavy chain CDR3 comprising SEQ ID NO:176, a light chain CDR1 comprising SEQ ID NO:177, a light chain CDR2 comprising SEQ ID NO:178, and a light chain CDR3 comprising SEQ ID NO:179.

In some embodiments, a C3-binding agent (e.g., an antibody) comprises (a) a heavy chain CDR1 comprising GYTFTDYWIN (SEQ ID NO:55), a heavy chain CDR2 comprising NIYPGSTSANYNEKFKS (SEQ ID NO:56), and a heavy chain CDR3 comprising YGYDSWFAY (SEQ ID NO:57), and/or (b) a light chain CDR1 comprising KSTKSLLNSDGFTYLD (SEQ ID NO:58), a light chain CDR2 comprising LVSNRFS (SEQ ID NO:59), and a light chain CDR3 comprising FQSNYLPLT (SEQ ID NO:60). In some embodiments, a C3-binding agent (e.g., an antibody) comprises (a) a heavy chain CDR1 comprising GYTFTDYWIN (SEQ ID NO:55), a heavy chain CDR2 comprising NIYPGSTSANYNEKFKS (SEQ ID NO:56), and a heavy chain CDR3 comprising YGYDSWFAY (SEQ ID NO:57), and (b) a light chain CDR1 comprising KSTKSLLNSDGFTYLD (SEQ ID NO:58), a light chain CDR2 comprising LVSNRFS (SEQ ID NO:59), and a light chain CDR3 comprising FQSNYLPLT (SEQ ID NO:60).

In some embodiments, a C3-binding agent (e.g., an antibody) comprises (a) a heavy chain variable region comprising a heavy chain CDR1 comprising GYTFTDYWIN (SEQ ID NO:55), a heavy chain CDR2 comprising NIYPGSTSANYNEKFKS (SEQ ID NO:56), and a heavy chain CDR3 comprising YGYDSWFAY (SEQ ID NO:57), and/or (b) a light chain variable region comprising a light chain CDR1 comprising KSTKSLLNSDGFTYLD (SEQ ID NO:58), a light chain CDR2 comprising LVSNRFS (SEQ ID NO:59), and a light chain CDR3 comprising FQSNYLPLT (SEQ ID NO:60). In some embodiments, a C3-binding agent (e.g., an antibody) comprises (a) a heavy chain variable region comprising a heavy chain CDR1 comprising GYTFTDYWIN (SEQ ID NO:55), a heavy chain CDR2 comprising NIYPGSTSANYNEKFKS (SEQ ID NO:56), and a heavy chain CDR3 comprising YGYDSWFAY (SEQ ID NO:57), and (b) a light chain variable region comprising a light chain CDR1 comprising KSTKSLLNSDGFTYLD (SEQ ID NO:58), a light chain CDR2 comprising LVSNRFS (SEQ ID NO:59), and a light chain CDR3 comprising FQSNYLPLT (SEQ ID NO:60).

In certain embodiments, a C3-binding agent comprises heavy chain CDRs 1, 2, and 3 of a heavy chain variable region comprising the amino acid sequence set forth in SEQ ID NO:97. In certain embodiments, a C3-binding agent comprises light chain CDRs 1, 2, and 3 of a light chain variable region comprising the amino acid sequence set forth in SEQ ID NO:98. In certain embodiments, a C3-binding agent comprises heavy chain CDRs 1, 2, and 3 of a heavy chain variable region comprising the amino acid sequence set forth in SEQ ID NO:97, and light chain CDRs 1, 2, and 3 of a light chain variable region comprising the amino acid sequence set forth in SEQ ID NO:98.

In some embodiments, a C3-binding agent (e.g., an antibody) comprises a heavy chain variable region having at least about 80%, about 85%, about 90%, or about 95% sequence identity to SEQ ID NO:97 and/or a light chain variable region having at least about 80%, about 85%, about 90%, or about 95% sequence identity to SEQ ID NO:98. In some embodiments, a C3-binding agent (e.g., an antibody) comprises a heavy chain variable region comprising SEQ ID NO:97 and/or a light chain variable region comprising SEQ ID NO:98. In some embodiments, a C3-binding agent (e.g., an antibody) comprises a heavy chain variable region of SEQ ID NO:97 and a light chain variable region of SEQ ID NO:98.

In certain embodiments, a C3-binding agent (e.g., an antibody) comprises (a) a heavy chain CDR1 comprising SEQ ID NO:61, a heavy chain CDR2 comprising SEQ ID NO:62, a heavy chain CDR3 comprising SEQ ID NO:63, a light chain CDR1 comprising SEQ ID NO:64, a light chain CDR2 comprising SEQ ID NO:65, and a light chain CDR3 comprising SEQ ID NO:66; (b) a heavy chain CDR1 comprising SEQ ID NO:180, a heavy chain CDR2 comprising SEQ ID NO:183, a heavy chain CDR3 comprising SEQ ID NO:63, a light chain CDR1 comprising SEQ ID NO:64, a light chain CDR2 comprising SEQ ID NO:65, and a light chain CDR3 comprising SEQ ID NO:66; (c) a heavy chain CDR1 comprising SEQ ID NO:61, a heavy chain CDR2 comprising SEQ ID NO:184, a heavy chain CDR3 comprising SEQ ID NO:63, a light chain CDR1 comprising SEQ ID NO:64, a light chain CDR2 comprising SEQ ID NO:65, and a light chain CDR3 comprising SEQ ID NO:66; (d) a heavy chain CDR1 comprising SEQ ID NO:181, a heavy chain CDR2 comprising SEQ ID NO:62, a heavy chain CDR3 comprising SEQ ID NO:63, a light chain CDR1 comprising SEQ ID NO:64, a light chain CDR2 comprising SEQ ID NO:65, and a light chain CDR3 comprising SEQ ID NO:66; or (e) a heavy chain CDR1 comprising SEQ ID NO:182, a heavy chain CDR2 comprising SEQ ID NO:185, a heavy chain CDR3 comprising SEQ ID NO:186, a light chain CDR1 comprising SEQ ID NO:187, a light chain CDR2 comprising SEQ ID NO:188, and a light chain CDR3 comprising SEQ ID NO:189.

In some embodiments, a C3-binding agent (e.g., an antibody) comprises (a) a heavy chain CDR1 comprising GYAFNSCWMN (SEQ ID NO:61), a heavy chain CDR2 comprising RIYPGDGDTNYNGKFKG (SEQ ID NO:62), and a heavy chain CDR3 comprising EGRNYGYEDY (SEQ ID NO:63), and/or (b) a light chain CDR1 comprising KASQSVDYDGDSYMN (SEQ ID NO:64), a light chain CDR2 comprising AASDLES (SEQ ID NO:65), and a light chain CDR3 comprising QQANEDPRT (SEQ ID NO:66). In some embodiments, a C3-binding agent (e.g., an antibody) comprises (a) a heavy chain CDR1 comprising GYAFNSCWMN (SEQ ID NO:61), a heavy chain CDR2 comprising RIYPGDGDTNYNGKFKG (SEQ ID NO:62), and a heavy chain CDR3 comprising EGRNYGYEDY (SEQ ID NO:63), and (b) a light chain CDR1 comprising KASQSVDYDGDSYMN (SEQ ID NO:64), a light chain CDR2 comprising AASDLES (SEQ ID NO:65), and a light chain CDR3 comprising QQANEDPRT (SEQ ID NO:66).

In some embodiments, a C3-binding agent (e.g., an antibody) comprises (a) a heavy chain variable region comprising a heavy chain CDR1 comprising GYAFNSCWMN (SEQ ID NO:61), a heavy chain CDR2 comprising RIYPGDGDTNYNGKFKG (SEQ ID NO:62), and a heavy chain CDR3 comprising EGRNYGYEDY (SEQ ID NO:63), and/or (b) a light chain variable region comprising a light chain CDR1 comprising KASQSVDYDGDSYMN (SEQ ID NO:64), a light chain CDR2 comprising AASDLES (SEQ ID NO:65), and a light chain CDR3 comprising QQANEDPRT (SEQ ID NO:66). In some embodiments, a C3-binding agent (e.g., an antibody) comprises (a) a heavy chain variable region comprising a heavy chain CDR1 comprising GYAFNSCWMN (SEQ ID NO:61), a heavy chain CDR2 comprising RIYPGDGDTNYNGKFKG (SEQ ID NO:62), and a heavy chain CDR3 comprising EGRNYGYEDY (SEQ ID NO:63), and (b) a light chain variable region comprising a light chain CDR1 comprising KASQSVDYDGDSYMN (SEQ ID NO:64), a light chain CDR2 comprising AASDLES (SEQ ID NO:65), and a light chain CDR3 comprising QQANEDPRT (SEQ ID NO:66).

In certain embodiments, a C3-binding agent comprises heavy chain CDRs 1, 2, and 3 of a heavy chain variable region comprising the amino acid sequence set forth in SEQ ID NO:99. In certain embodiments, a C3-binding agent comprises light chain CDRs 1, 2, and 3 of a light chain variable region comprising the amino acid sequence set forth in SEQ ID NO:100. In certain embodiments, a C3-binding agent comprises heavy chain CDRs 1, 2, and 3 of a heavy chain variable region comprising the amino acid sequence set forth in SEQ ID NO:99, and light chain CDRs 1, 2, and 3 of a light chain variable region comprising the amino acid sequence set forth in SEQ ID NO:100.

In some embodiments, a C3-binding agent (e.g., an antibody) comprises a heavy chain variable region having at least about 80%, about 85%, about 90%, or about 95% sequence identity to SEQ ID NO:99 and/or a light chain variable region having at least about 80%, about 85%, about 90%, or about 95% sequence identity to SEQ ID NO:100. In some embodiments, a C3-binding agent (e.g., an antibody) comprises a heavy chain variable region comprising SEQ ID NO:99 and/or a light chain variable region comprising SEQ ID NO:100. In some embodiments, a C3-binding agent (e.g., an antibody) comprises a heavy chain variable region of SEQ ID NO:99 and a light chain variable region of SEQ ID NO:100.

In certain embodiments, a C3-binding agent (e.g., an antibody) comprises (a) a heavy chain CDR1 comprising SEQ ID NO:67, a heavy chain CDR2 comprising SEQ ID NO:68, a heavy chain CDR3 comprising SEQ ID NO:69, a light chain CDR1 comprising SEQ ID NO:70, a light chain CDR2 comprising SEQ ID NO:71, and a light chain CDR3 comprising SEQ ID NO:72; (b) a heavy chain CDR1 comprising SEQ ID NO:190, a heavy chain CDR2 comprising SEQ ID NO:193, a heavy chain CDR3 comprising SEQ ID NO:69, a light chain CDR1 comprising SEQ ID NO:70, a light chain CDR2 comprising SEQ ID NO:71, and a light chain CDR3 comprising SEQ ID NO:72; (c) a heavy chain CDR1 comprising SEQ ID NO:67, a heavy chain CDR2 comprising SEQ ID NO:194, a heavy chain CDR3 comprising SEQ ID NO:69, a light chain CDR1 comprising SEQ ID NO:70, a light chain CDR2 comprising SEQ ID NO:71, and a light chain CDR3 comprising SEQ ID NO:72; (d) a heavy chain CDR1 comprising SEQ ID NO:191, a heavy chain CDR2 comprising SEQ ID NO:68, a heavy chain CDR3 comprising SEQ ID NO:69, a light chain CDR1 comprising SEQ ID NO:70, a light chain CDR2 comprising SEQ ID NO:71, and a light chain CDR3 comprising SEQ ID NO:72; or (e) a heavy chain CDR1 comprising SEQ ID NO:192, a heavy chain CDR2 comprising SEQ ID NO:195, a heavy chain CDR3 comprising SEQ ID NO:196, a light chain CDR1 comprising SEQ ID NO:197, a light chain CDR2 comprising SEQ ID NO:198, and a light chain CDR3 comprising SEQ ID NO:199.

In some embodiments, a C3-binding agent (e.g., an antibody) comprises (a) a heavy chain CDR1 comprising GFTFSNYAMS (SEQ ID NO:67), a heavy chain CDR2 comprising QTISSGGRYTYYPDSVKG (SEQ ID NO:68), and a heavy chain CDR3 comprising RYYGNSYWYFDV (SEQ ID NO:69), and/or (b) a light chain CDR1 comprising KSSQSLLNSGNQKHYLT (SEQ ID NO:70), a light chain CDR2 comprising GASTRGS (SEQ ID NO:71), and a light chain CDR3 comprising QNDHSYPYT (SEQ ID NO:72). In some embodiments, a C3-binding agent (e.g., an antibody) comprises (a) a heavy chain CDR1 comprising GFTFSNYAMS (SEQ ID NO:67), a heavy chain CDR2 comprising QTISSGGRYTYYPDSVKG (SEQ ID NO:68), and a heavy chain CDR3 comprising RYYGNSYWYFDV (SEQ ID NO:69), and (b) a light chain CDR1 comprising KSSQSLLNSGNQKHYLT (SEQ ID NO:70), a light chain CDR2 comprising GASTRGS (SEQ ID NO:71), and a light chain CDR3 comprising QNDHSYPYT (SEQ ID NO:72).

In some embodiments, a C3-binding agent (e.g., an antibody) comprises (a) a heavy chain variable region comprising a heavy chain CDR1 comprising GFTFSNYAMS (SEQ ID NO:67), a heavy chain CDR2 comprising QTISSGGRYTYYPDSVKG (SEQ ID NO:68), and a heavy chain CDR3 comprising RYYGNSYWYFDV (SEQ ID NO:69), and/or (b) a light chain variable region comprising a light chain CDR1 comprising KSSQSLLNSGNQKHYLT (SEQ ID NO:70), a light chain CDR2 comprising GASTRGS (SEQ ID NO:71), and a light chain CDR3 comprising QNDHSYPYT (SEQ ID NO:72). In some embodiments, a C3-binding agent (e.g., an antibody) comprises (a) a heavy chain variable region comprising a heavy chain CDR1 comprising GFTFSNYAMS (SEQ ID NO:67), a heavy chain CDR2 comprising QTISSGGRYTYYPDSVKG (SEQ ID NO:68), and a heavy chain CDR3 comprising RYYGNSYWYFDV (SEQ ID NO:69), and (b) a light chain variable region comprising a light chain CDR1 comprising KSSQSLLNSGNQKHYLT (SEQ ID NO:70), a light chain CDR2 comprising GASTRGS (SEQ ID NO:71), and a light chain CDR3 comprising QNDHSYPYT (SEQ ID NO:72).

In certain embodiments, a C3-binding agent comprises heavy chain CDRs 1, 2, and 3 of a heavy chain variable region comprising the amino acid sequence set forth in SEQ ID NO:101. In certain embodiments, a C3-binding agent comprises light chain CDRs 1, 2, and 3 of a light chain variable region comprising the amino acid sequence set forth in SEQ ID NO:102. In certain embodiments, a C3-binding agent comprises heavy chain CDRs 1, 2, and 3 of a heavy chain variable region comprising the amino acid sequence set forth in SEQ ID NO:101, and light chain CDRs 1, 2, and 3 of a light chain variable region comprising the amino acid sequence set forth in SEQ ID NO:102.

In some embodiments, a C3-binding agent (e.g., an antibody) comprises a heavy chain variable region having at least about 80%, about 85%, about 90%, or about 95% sequence identity to SEQ ID NO:101 and/or a light chain variable region having at least about 80%, about 85%, about 90%, or about 95% sequence identity to SEQ ID NO:102. In some embodiments, a C3-binding agent (e.g., an antibody) comprises a heavy chain variable region comprising SEQ ID NO:101 and/or a light chain variable region comprising SEQ ID NO:102. In some embodiments, a C3-binding agent (e.g., an antibody) comprises a heavy chain variable region of SEQ ID NO:101 and a light chain variable region of SEQ ID NO:102.

In certain embodiments, a C3-binding agent (e.g., an antibody) comprises (a) a heavy chain CDR1 comprising SEQ ID NO:73, a heavy chain CDR2 comprising SEQ ID NO:74, a heavy chain CDR3 comprising SEQ ID NO:75, a light chain CDR1 comprising SEQ ID NO:76, a light chain CDR2 comprising SEQ ID NO:77, and a light chain CDR3 comprising SEQ ID NO:78; (b) a heavy chain CDR1 comprising SEQ ID NO:200, a heavy chain CDR2 comprising SEQ ID NO:203, a heavy chain CDR3 comprising SEQ ID NO:75, a light chain CDR1 comprising SEQ ID NO:76, a light chain CDR2 comprising SEQ ID NO:77, and a light chain CDR3 comprising SEQ ID NO:78; (c) a heavy chain CDR1 comprising SEQ ID NO:73, a heavy chain CDR2 comprising SEQ ID NO:204, a heavy chain CDR3 comprising SEQ ID NO:75, a light chain CDR1 comprising SEQ ID NO:76, a light chain CDR2 comprising SEQ ID NO:77, and a light chain CDR3 comprising SEQ ID NO:78; (d) a heavy chain CDR1 comprising SEQ ID NO:201, a heavy chain CDR2 comprising SEQ ID NO:74, a heavy chain CDR3 comprising SEQ ID NO:75, a light chain CDR1 comprising SEQ ID NO:76, a light chain CDR2 comprising SEQ ID NO:77, and a light chain CDR3 comprising SEQ ID NO:78; or (e) a heavy chain CDR1 comprising SEQ ID NO:202, a heavy chain CDR2 comprising SEQ ID NO:205, a heavy chain CDR3 comprising SEQ ID NO:206, a light chain CDR1 comprising SEQ ID NO:207, a light chain CDR2 comprising SEQ ID NO:208, and a light chain CDR3 comprising SEQ ID NO:209.

In some embodiments, a C3-binding agent (e.g., an antibody) comprises (a) a heavy chain CDR1 comprising GFTFSSYTMS (SEQ ID NO:73), a heavy chain CDR2 comprising YISSGGGTTYYPDTVKG (SEQ ID NO:74), and a heavy chain CDR3 comprising RYYRGSSLWYFDV (SEQ ID NO:75), and/or (b) a light chain CDR1 comprising KSSQSLFNSGSQKNFLT (SEQ ID NO:76), a light chain CDR2 comprising WASTRES (SEQ ID NO:77), and a light chain CDR3 comprising QNDYSYPLT (SEQ ID NO:78). In some embodiments, a C3-binding agent (e.g., an antibody) comprises (a) a heavy chain CDR1 comprising GFTFSSYTMS (SEQ ID NO:73), a heavy chain CDR2 comprising YISSGGGTTYYPDTVKG (SEQ ID NO:74), and a heavy chain CDR3 comprising RYYRGSSLWYFDV (SEQ ID NO:75), and (b) a light chain CDR1 comprising KSSQSLFNSGSQKNFLT (SEQ ID NO:76), a light chain CDR2 comprising WASTRES (SEQ ID NO:77), and a light chain CDR3 comprising QNDYSYPLT (SEQ ID NO:78).

In some embodiments, a C3-binding agent (e.g., an antibody) comprises (a) a heavy chain variable region comprising a heavy chain CDR1 comprising GFTFSSYTMS (SEQ ID NO:73), a heavy chain CDR2 comprising YISSGGGTTYYPDTVKG (SEQ ID NO:74), and a heavy chain CDR3 comprising RYYRGSSLWYFDV (SEQ ID NO:75), and/or (b) a light chain variable region comprising a light chain CDR1 comprising KSSQSLFNSGSQKNFLT (SEQ ID NO:76), a light chain CDR2 comprising WASTRES (SEQ ID NO:77), and a light chain CDR3 comprising QNDYSYPLT (SEQ ID NO:78). In some embodiments, a C3-binding agent (e.g., an antibody) comprises (a) a heavy chain variable region comprising a heavy chain CDR1 comprising GFTFSSYTMS (SEQ ID NO:73), a heavy chain CDR2 comprising YISSGGGTTYYPDTVKG (SEQ ID NO:74), and a heavy chain CDR3 comprising RYYRGSSLWYFDV (SEQ ID NO:75), and (b) a light chain variable region comprising a light chain CDR1 comprising KSSQSLFNSGSQKNFLT (SEQ ID NO:76), a light chain CDR2 comprising WASTRES (SEQ ID NO:77), and a light chain CDR3 comprising QNDYSYPLT (SEQ ID NO:78).

In certain embodiments, a C3-binding agent comprises heavy chain CDRs 1, 2, and 3 of a heavy chain variable region comprising the amino acid sequence set forth in SEQ ID NO:103. In certain embodiments, a C3-binding agent comprises light chain CDRs 1, 2, and 3 of a light chain variable region comprising the amino acid sequence set forth in SEQ ID NO:104. In certain embodiments, a C3-binding agent comprises heavy chain CDRs 1, 2, and 3 of a heavy chain variable region comprising the amino acid sequence set forth in SEQ ID NO:103, and light chain CDRs 1, 2, and 3 of a light chain variable region comprising the amino acid sequence set forth in SEQ ID NO:104.

In some embodiments, a C3-binding agent (e.g., an antibody) comprises a heavy chain variable region having at least about 80%, about 85%, about 90%, or about 95% sequence identity to SEQ ID NO:103 and/or a light chain variable region having at least about 80%, about 85%, about 90%, or about 95% sequence identity to SEQ ID NO:104. In some embodiments, a C3-binding agent (e.g., an antibody) comprises a heavy chain variable region comprising SEQ ID NO:103 and/or a light chain variable region comprising SEQ ID NO:104. In some embodiments, a C3-binding agent (e.g., an antibody) comprises a heavy chain variable region of SEQ ID NO:103 and a light chain variable region of SEQ ID NO:104.

In certain embodiments, a C3-binding agent (e.g., an antibody) comprises (a) a heavy chain CDR1 comprising SEQ ID NO:79, a heavy chain CDR2 comprising SEQ ID NO:80, a heavy chain CDR3 comprising SEQ ID NO:81, a light chain CDR1 comprising SEQ ID NO:82, a light chain CDR2 comprising SEQ ID NO:83, and a light chain CDR3 comprising SEQ ID NO:84; (b) a heavy chain CDR1 comprising SEQ ID NO:210, a heavy chain CDR2 comprising SEQ ID NO:213, a heavy chain CDR3 comprising SEQ ID NO:81, a light chain CDR1 comprising SEQ ID NO:82, a light chain CDR2 comprising SEQ ID NO:83, and a light chain CDR3 comprising SEQ ID NO:84; (c) a heavy chain CDR1 comprising SEQ ID NO:79, a heavy chain CDR2 comprising SEQ ID NO:214, a heavy chain CDR3 comprising SEQ ID NO:81, a light chain CDR1 comprising SEQ ID NO:82, a light chain CDR2 comprising SEQ ID NO:83, and a light chain CDR3 comprising SEQ ID NO:84; (d) a heavy chain CDR1 comprising SEQ ID NO:211, a heavy chain CDR2 comprising SEQ ID NO:80, a heavy chain CDR3 comprising SEQ ID NO:81, a light chain CDR1 comprising SEQ ID NO:82, a light chain CDR2 comprising SEQ ID NO:83, and a light chain CDR3 comprising SEQ ID NO:84; or (e) a heavy chain CDR1 comprising SEQ ID NO:212, a heavy chain CDR2 comprising SEQ ID NO:215, a heavy chain CDR3 comprising SEQ ID NO:216, a light chain CDR1 comprising SEQ ID NO:217, a light chain CDR2 comprising SEQ ID NO:218, and a light chain CDR3 comprising SEQ ID NO:219.

In some embodiments, a C3-binding agent (e.g., an antibody) comprises (a) a heavy chain CDR1 comprising GYSITSGYSLH (SEQ ID NO:79), a heavy chain CDR2 comprising YIHYSGSTNYNPSLKS (SEQ ID NO:80), and a heavy chain CDR3 comprising AWDYLDY (SEQ ID NO:81), and/or (b) a light chain CDR1 comprising RASENIYSQLA (SEQ ID NO:82), a light chain CDR2 comprising DAKTLAE (SEQ ID NO:83), and a light chain CDR3 comprising HHHFGILYT (SEQ ID NO:84). In some embodiments, a C3-binding agent (e.g., an antibody) comprises (a) a heavy chain CDR1 comprising GYSITSGYSLH (SEQ ID NO:79), a heavy chain CDR2 comprising YIHYSGSTNYNPSLKS (SEQ ID NO:80), and a heavy chain CDR3 comprising AWDYLDY (SEQ ID NO:81), and (b) a light chain CDR1 comprising RASENIYSQLA (SEQ ID NO:82), a light chain CDR2 comprising DAKTLAE (SEQ ID NO:83), and a light chain CDR3 comprising HHHFGILYT (SEQ ID NO:84).

In some embodiments, a C3-binding agent (e.g., an antibody) comprises (a) a heavy chain variable region comprising heavy chain CDR1 comprising GYSITSGYSLH (SEQ ID NO:79), a heavy chain CDR2 comprising YIHYSGSTNYNPSLKS (SEQ ID NO:80), and a heavy chain CDR3 comprising AWDYLDY (SEQ ID NO:81), and/or (b) a light chain variable region comprising a light chain CDR1 comprising RASENIYSQLA (SEQ ID NO:82), a light chain CDR2 comprising DAKTLAE (SEQ ID NO:83), and a light chain CDR3 comprising HHHFGILYT (SEQ ID NO:84). In some embodiments, a C3-binding agent (e.g., an antibody) comprises (a) a heavy chain variable region comprising a heavy chain CDR1 comprising GYSITSGYSLH (SEQ ID NO:79), a heavy chain CDR2 comprising YIHYSGSTNYNPSLKS (SEQ ID NO:80), and a heavy chain CDR3 comprising AWDYLDY (SEQ ID NO:81), and (b) a light chain variable region comprising a light chain CDR1 comprising RASENIYSQLA (SEQ ID NO:82), a light chain CDR2 comprising DAKTLAE (SEQ ID NO:83), and a light chain CDR3 comprising HHHFGILYT (SEQ ID NO:84).

In certain embodiments, a C3-binding agent comprises heavy chain CDRs 1, 2, and 3 of a heavy chain variable region comprising the amino acid sequence set forth in SEQ ID NO:105. In certain embodiments, a C3-binding agent comprises light chain CDRs 1, 2, and 3 of a light chain variable region comprising the amino acid sequence set forth in SEQ ID NO:106. In certain embodiments, a C3-binding agent comprises heavy chain CDRs 1, 2, and 3 of a heavy chain variable region comprising the amino acid sequence set forth in SEQ ID NO:105, and light chain CDRs 1, 2, and 3 of a light chain variable region comprising the amino acid sequence set forth in SEQ ID NO:106.

In some embodiments, a C3-binding agent (e.g., an antibody) comprises a heavy chain variable region having at least about 80%, about 85%, about 90%, or about 95% sequence identity to SEQ ID NO:105 and/or a light chain variable region having at least about 80%, about 85%, about 90%, or about 95% sequence identity to SEQ ID NO:106. In some embodiments, a C3-binding agent (e.g., an antibody) comprises a heavy chain variable region comprising SEQ ID NO:105 and/or a light chain variable region comprising SEQ ID NO:106. In some embodiments, a C3-binding agent (e.g., an antibody) comprises a heavy chain variable region of SEQ ID NO:105 and a light chain variable region of SEQ ID NO:106.

In certain embodiments, a C3-binding agent (e.g., an antibody) comprises (a) a heavy chain CDR1 comprising SEQ ID NO:85, a heavy chain CDR2 comprising SEQ ID NO:86, a heavy chain CDR3 comprising SEQ ID NO:87, a light chain CDR1 comprising SEQ ID NO:88, a light chain CDR2 comprising SEQ ID NO:89, and a light chain CDR3 comprising SEQ ID NO:90; (b) a heavy chain CDR1 comprising SEQ ID NO:210, a heavy chain CDR2 comprising SEQ ID NO:222, a heavy chain CDR3 comprising SEQ ID NO:87, a light chain CDR1 comprising SEQ ID NO:88, a light chain CDR2 comprising SEQ ID NO:89, and a light chain CDR3 comprising SEQ ID NO:90; (c) a heavy chain CDR1 comprising SEQ ID NO:85, a heavy chain CDR2 comprising SEQ ID NO:223, a heavy chain CDR3 comprising SEQ ID NO:87, a light chain CDR1 comprising SEQ ID NO:88, a light chain CDR2 comprising SEQ ID NO:89, and a light chain CDR3 comprising SEQ ID NO:90; (d) a heavy chain CDR1 comprising SEQ ID NO:220, a heavy chain CDR2 comprising SEQ ID NO:86, a heavy chain CDR3 comprising SEQ ID NO:87, a light chain CDR1 comprising SEQ ID NO:88, a light chain CDR2 comprising SEQ ID NO:89, and a light chain CDR3 comprising SEQ ID NO:90; or (e) a heavy chain CDR1 comprising SEQ ID NO:221, a heavy chain CDR2 comprising SEQ ID NO:224, a heavy chain CDR3 comprising SEQ ID NO:225, a light chain CDR1 comprising SEQ ID NO:226, a light chain CDR2 comprising SEQ ID NO:227, and a light chain CDR3 comprising SEQ ID NO:228.

In some embodiments, a C3-binding agent (e.g., an antibody) comprises (a) a heavy chain CDR1 comprising GYSITSGYYWN (SEQ ID NO:85), a heavy chain CDR2 comprising YIRYDGSNNYNPSLKN (SEQ ID NO:86), and a heavy chain CDR3 comprising HYGYDGGAFDF (SEQ ID NO:87), and/or (b) a light chain CDR1 comprising RTSENIYNYLV (SEQ ID NO:88), a light chain CDR2 comprising NAKTLEE (SEQ ID NO:89), and a light chain CDR3 comprising QHHYGTPFT (SEQ ID NO:90). In some embodiments, a C3-binding agent (e.g., an antibody) comprises (a) a heavy chain CDR1 comprising GYSITSGYYWN (SEQ ID NO:85), a heavy chain CDR2 comprising YIRYDGSNNYNPSLKN (SEQ ID NO:86), and a heavy chain CDR3 comprising HYGYDGGAFDF (SEQ ID NO:87), and (b) a light chain CDR1 comprising RTSENIYNYLV (SEQ ID NO:88), a light chain CDR2 comprising NAKTLEE (SEQ ID NO:89), and a light chain CDR3 comprising QHHYGTPFT (SEQ ID NO:90).

In some embodiments, a C3-binding agent (e.g., an antibody) comprises (a) a heavy chain variable region comprising a heavy chain CDR1 comprising GYSITSGYYWN (SEQ ID NO:85), a heavy chain CDR2 comprising YIRYDGSNNYNPSLKN (SEQ ID NO:86), and a heavy chain CDR3 comprising HYGYDGGAFDF (SEQ ID NO:87), and/or (b) a light chain variable region comprising a light chain CDR1 comprising RTSENIYNYLV (SEQ ID NO:88), a light chain CDR2 comprising NAKTLEE (SEQ ID NO:89), and a light chain CDR3 comprising QHHYGTPFT (SEQ ID NO:90). In some embodiments, a C3-binding agent (e.g., an antibody) comprises (a) a heavy chain variable region comprising a heavy chain CDR1 comprising GYSITSGYYWN (SEQ ID NO:85), a heavy chain CDR2 comprising YIRYDGSNNYNPSLKN (SEQ ID NO:86), and a heavy chain CDR3 comprising HYGYDGGAFDF (SEQ ID NO:87), and (b) a light chain variable region comprising a light chain CDR1 comprising RTSENIYNYLV (SEQ ID NO:88), a light chain CDR2 comprising NAKTLEE (SEQ ID NO:89), and a light chain CDR3 comprising QHHYGTPFT (SEQ ID NO:90).

In certain embodiments, a C3-binding agent comprises heavy chain CDRs 1, 2, and 3 of a heavy chain variable region comprising the amino acid sequence set forth in SEQ ID NO:107. In certain embodiments, a C3-binding agent comprises light chain CDRs 1, 2, and 3 of a light chain variable region comprising the amino acid sequence set forth in SEQ ID NO:108. In certain embodiments, a C3-binding agent comprises heavy chain CDRs 1, 2, and 3 of a heavy chain variable region comprising the amino acid sequence set forth in SEQ ID NO:107, and light chain CDRs 1, 2, and 3 of a light chain variable region comprising the amino acid sequence set forth in SEQ ID NO:108.

In some embodiments, a C3-binding agent (e.g., an antibody) comprises a heavy chain variable region having at least about 80%, about 85%, about 90%, or about 95% sequence identity to SEQ ID NO:107 and/or a light chain variable region having at least about 80%, about 85%, about 90%, or about 95% sequence identity to SEQ ID NO:108. In some embodiments, a C3-binding agent (e.g., an antibody) comprises a heavy chain variable region comprising SEQ ID NO:107 and/or a light chain variable region comprising SEQ ID NO:108. In some embodiments, a C3-binding agent (e.g., an antibody) comprises a heavy chain variable region of SEQ ID NO:107 and a light chain variable region of SEQ ID NO:108.

In some embodiments, a C3-binding agent (e.g., an antibody) is a scFv. In some embodiments, a scFv comprises a heavy chain variable region comprising SEQ ID NO:110 or SEQ ID NO:111. In some embodiments, a scFv comprises a light chain variable region comprising SEQ ID NO:112. In some embodiments, a scFv comprises a heavy chain variable region comprising SEQ ID NO:110 and a light chain variable region comprising SEQ ID NO:112. In some embodiments, a scFv comprises a heavy chain variable region comprising SEQ ID NO:111 and a light chain variable region comprising SEQ ID NO:112. In some embodiments, a scFv comprises SEQ ID NO:113. In some embodiments, a scFv comprises SEQ ID NO:114. In some embodiments, a scFv comprises SEQ ID NO:119. In some embodiments, a scFv comprises SEQ ID NO:229.

Provided in this disclosure are antibodies that compete with one or more of the binding agents described herein for binding to C3. In some embodiments, antibodies provided herein compete with one or more of the C3-binding agents described herein for binding to human C3. In some embodiments, an antibody provided herein binds the same epitope as one of the antibodies described herein. In some embodiments, an antibody provided herein binds an epitope overlapping with an epitope bound by one of the antibodies described herein. Antibodies and antigen-binding fragments that compete with, or bind to the same epitope, as the antibodies described herein are expected to show similar functional properties.

In some embodiments, an antibody competes for binding to C3 with a C3-binding agent (e.g., an antibody) described herein. In some embodiments, an antibody competes for binding to human C3 with a C3-binding agent (e.g., an antibody) described herein. In some embodiments, an antibody competes for binding to C3 (e.g., human C3) with a reference antibody, wherein the reference antibody comprises: (a) a heavy chain variable region comprising a heavy chain CDR1 comprising GYTFTDFYMD (SEQ ID NO:7), a heavy chain CDR2 comprising YIYPHNGGTTYNQNFTG (SEQ ID NO:8), YIYPHNGGTTYNQQFTG (SEQ ID NO:13), YIYPHNAGTTYNQQFTG (SEQ ID NO:14), YIYPHNTGTTYNQQFTG (SEQ ID NO:15), YIYPHEGGTTYNQQFTG (SEQ ID NO:16), or YIYPHQGGTTYNQQFTG (SEQ ID NO:17), and a heavy chain CDR3 comprising RGGFDFDY (SEQ ID NO:9); and/or (b) a light chain variable region comprising a light chain CDR1 comprising KASENVDTYVS (SEQ ID NO:10), a light chain CDR2 comprising GASNRYT (SEQ ID NO:11), and a light chain CDR3 comprising GQSHSYPLT (SEQ ID NO:12). In some embodiments, an antibody competes for binding to C3 (e.g., human C3) with a reference antibody, wherein the reference antibody comprises (a) a heavy chain variable region comprising a heavy chain CDR1 comprising GYTFTDFYMD (SEQ ID NO:7), a heavy chain CDR2 comprising YIYPHNGGTTYNQNFTG (SEQ ID NO:8), and a heavy chain CDR3 comprising RGGFDFDY (SEQ ID NO:9); and (b) a light chain variable region comprising a light chain CDR1 comprising KASENVDTYVS (SEQ ID NO:10), a light chain CDR2 comprising GASNRYT (SEQ ID NO:11), and a light chain CDR3 comprising GQSHSYPLT (SEQ ID NO:12). In some embodiments, an antibody competes for binding to C3 (e.g., human C3) with a reference antibody, wherein the reference antibody comprises (a) a heavy chain variable region comprising a heavy chain CDR1 comprising GYTFTDFYMD (SEQ ID NO:7), a heavy chain CDR2 comprising YIYPHNGGTTYNQQFTG (SEQ ID NO:13), and a heavy chain CDR3 comprising RGGFDFDY (SEQ ID NO:9); and (b) a light chain variable region comprising a light chain CDR1 comprising KASENVDTYVS (SEQ ID NO: 10), a light chain CDR2 comprising GASNRYT (SEQ ID NO:11), and a light chain CDR3 comprising GQSHSYPLT (SEQ ID NO:12). In some embodiments, an antibody competes for binding to C3 (e.g., human C3) with a reference antibody, wherein the reference antibody comprises (a) a heavy chain variable region comprising a heavy chain CDR1 comprising GYTFTDFYMD (SEQ ID NO:7), a heavy chain CDR2 comprising YIYPHNAGTTYNQQFTG (SEQ ID NO:14), and a heavy chain CDR3 comprising RGGFDFDY (SEQ ID NO:9); and (b) a light chain variable region comprising a light chain CDR1 comprising KASENVDTYVS (SEQ ID NO:10), a light chain CDR2 comprising GASNRYT (SEQ ID NO:11), and a light chain CDR3 comprising GQSHSYPLT (SEQ ID NO:12). In some embodiments, an antibody competes for binding to C3 (e.g., human C3) with a reference antibody, wherein the reference antibody comprises (a) a heavy chain variable region comprising a heavy chain CDR1 comprising GYTFTDFYMD (SEQ ID NO:7), a heavy chain CDR2 comprising YIYPHNTGTTYNQQFTG (SEQ ID NO:15), and a heavy chain CDR3 comprising RGGFDFDY (SEQ ID NO:9); and (b) a light chain variable region comprising a light chain CDR1 comprising KASENVDTYVS (SEQ ID NO:10), a light chain CDR2 comprising GASNRYT (SEQ ID NO:11), and a light chain CDR3 comprising GQSHSYPLT (SEQ ID NO:12). In some embodiments, an antibody competes for binding to C3 (e.g., human C3) with a reference antibody, wherein the reference antibody comprises (a) a heavy chain variable region comprising a heavy chain CDR1 comprising GYTFTDFYMD (SEQ ID NO:7), a heavy chain CDR2 comprising YIYPHEGGTTYNQQFTG (SEQ ID NO:16), and a heavy chain CDR3 comprising RGGFDFDY (SEQ ID NO:9); and (b) a light chain variable region comprising a light chain CDR1 comprising KASENVDTYVS (SEQ ID NO:10), a light chain CDR2 comprising GASNRYT (SEQ ID NO:11), and a light chain CDR3 comprising GQSHSYPLT (SEQ ID NO:12). In some embodiments, an antibody competes for binding to C3 (e.g., human C3) with a reference antibody, wherein the reference antibody comprises (a) a heavy chain variable region comprising a heavy chain CDR1 comprising GYTFTDFYMD (SEQ ID NO:7), a heavy chain CDR2 comprising YIYPHQGGTTYNQQFTG (SEQ ID NO:17), and a heavy chain CDR3 comprising RGGFDFDY (SEQ ID NO:9); and (b) a light chain variable region comprising a light chain CDR1 comprising KASENVDTYVS (SEQ ID NO:10), a light chain CDR2 comprising GASNRYT (SEQ ID NO:11), and a light chain CDR3 comprising GQSHSYPLT (SEQ ID NO:12).

In some embodiments, an antibody competes for binding to C3 (e.g., human C3) with a reference antibody, wherein the reference antibody comprises: (a) a heavy chain variable region comprising SEQ ID NO:18 and (b) a light chain variable region comprising SEQ ID NO:19. In some embodiments, an antibody competes for binding to C3 (e.g., human C3) with a reference antibody, wherein the reference antibody comprises: (a) a heavy chain variable region comprising SEQ ID NO:20, SEQ ID NO:21, SEQ ID NO:22, SEQ ID NO:23, or SEQ ID NO:24; and (b) a light chain variable region comprising SEQ ID NO:25. In some embodiments, an antibody competes for specific binding to C3 (e.g., human C3) with a reference antibody, wherein the reference antibody comprises: (a) a heavy chain variable region comprising SEQ ID NO:20 and (b) a light chain variable region comprising SEQ ID NO:25. In some embodiments, an antibody competes for specific binding to C3 (e.g., human C3) with a reference antibody, wherein the reference antibody comprises: (a) a heavy chain variable region comprising SEQ ID NO:21 and (b) a light chain variable region comprising SEQ ID NO:25. In some embodiments, an antibody competes for specific binding to C3 (e.g., human C3) with a reference antibody, wherein the reference antibody comprises: (a) a heavy chain variable region comprising SEQ ID NO:22 and (b) a light chain variable region comprising SEQ ID NO:25. In some embodiments, an antibody competes for specific binding to C3 (e.g., human C3) with a reference antibody, wherein the reference antibody comprises: (a) a heavy chain variable region comprising SEQ ID NO:23 and (b) a light chain variable region comprising SEQ ID NO:25. In some embodiments, an antibody competes for specific binding to C3 (e.g., human C3) with a reference antibody, wherein the reference antibody comprises: (a) a heavy chain variable region comprising SEQ ID NO:24 and (b) a light chain variable region comprising SEQ ID NO:25.

In some embodiments, an antibody competes for binding to C3 (e.g. human C3) with a reference antibody, wherein the reference antibody comprises (a) a heavy chain CDR1 comprising GYSFTGYNMN (SEQ ID NO:38), a heavy chain CDR2 comprising NINPYYGSTNYNQKFKG (SEQ ID NO:39), and a heavy chain CDR3 comprising GYYGGNYPFAY (SEQ ID NO:40), and/or (b) a light chain CDR1 comprising RASENIYSYLA (SEQ ID NO:41), a light chain CDR2 comprising NAKTLAE (SEQ ID NO:42), and a light chain CDR3 comprising QHYYGTPYT (SEQ ID NO:43). In some embodiments, an antibody competes for binding to C3 (e.g. human C3) with a reference antibody, wherein the reference antibody comprises (a) a heavy chain CDR1 comprising GYSFTGYNMN (SEQ ID NO:38), a heavy chain CDR2 comprising NINPYYDSTSYNQKFKG (SEQ ID NO:44), and a heavy chain CDR3 comprising ENYDFVGFAY (SEQ ID NO:45), and/or (b) a light chain CDR1 comprising RASSSVSYMH (SEQ ID NO:46), a light chain CDR2 comprising VTSNLAS (SEQ ID NO:47), and a light chain CDR3 comprising QQWSTNPLT (SEQ ID NO:48). In some embodiments, an antibody competes for binding to C3 (e.g. human C3) with a reference antibody, wherein the reference antibody comprises (a) a heavy chain CDR1 comprising GYSFTGYNMH (SEQ ID NO:49), a heavy chain CDR2 comprising NINPYYGTTNSNQKFED (SEQ ID NO:50), and a heavy chain CDR3 comprising GIYYYGTGYPYFDF (SEQ ID NO:51), and/or (b) a light chain CDR1 comprising RASQDINNYLN (SEQ ID NO:52), a light chain CDR2 comprising YTSRLHS (SEQ ID NO:53), and a light chain CDR3 comprising QQGITLPWT (SEQ ID NO:54). In some embodiments, an antibody competes for binding to C3 (e.g. human C3) with a reference antibody, wherein the reference antibody comprises (a) a heavy chain CDR1 comprising GYTFTDYWIN (SEQ ID NO:55), a heavy chain CDR2 comprising NIYPGSTSANYNEKFKS (SEQ ID NO:56), and a heavy chain CDR3 comprising YGYDSWFAY (SEQ ID NO:57), and/or (b) a light chain CDR1 comprising KSTKSLLNSDGFTYLD (SEQ ID NO:58), a light chain CDR2 comprising LVSNRFS (SEQ ID NO:59), and a light chain CDR3 comprising FQSNYLPLT (SEQ ID NO:60). In some embodiments, an antibody competes for binding to C3 (e.g. human C3) with a reference antibody, wherein the reference antibody comprises (a) a heavy chain CDR1 comprising GYAFNSCWMN (SEQ ID NO:61), a heavy chain CDR2 comprising RIYPGDGDTNYNGKFKG (SEQ ID NO:62), and a heavy chain CDR3 comprising EGRNYGYEDY (SEQ ID NO:63), and/or (b) a light chain CDR1 comprising KASQSVDYDGDSYMN (SEQ ID NO:64), a light chain CDR2 comprising AASDLES (SEQ ID NO:65), and a light chain CDR3 comprising QQANEDPRT (SEQ ID NO:66). In some embodiments, an antibody competes for binding to C3 (e.g. human C3) with a reference antibody, wherein the reference antibody comprises (a) a heavy chain CDR1 comprising GFTFSNYAMS (SEQ ID NO:67), a heavy chain CDR2 comprising QTISSGGRYTYYPDSVKG (SEQ ID NO:68), and a heavy chain CDR3 comprising RYYGNSYWYFDV (SEQ ID NO:69), and/or (b) a light chain CDR1 comprising KSSQSLLNSGNQKHYLT (SEQ ID NO:70), a light chain CDR2 comprising GASTRGS (SEQ ID NO:71), and a light chain CDR3 comprising QNDHSYPYT (SEQ ID NO:72). In some embodiments, an antibody competes for binding to C3 (e.g. human C3) with a reference antibody, wherein the reference antibody comprises (a) a heavy chain CDR1 comprising GFTFSSYTMS (SEQ ID NO:73), a heavy chain CDR2 comprising YISSGGGTTYYPDTVKG (SEQ ID NO:74), and a heavy chain CDR3 comprising RYYRGSSLWYFDV (SEQ ID NO:75), and/or (b) a light chain CDR1 comprising KSSQSLFNSGSQKNFLT (SEQ ID NO:76), a light chain CDR2 comprising WASTRES (SEQ ID NO:77), and a light chain CDR3 comprising QNDYSYPLT (SEQ ID NO:78). In some embodiments, an antibody competes for binding to C3 (e.g. human C3) with a reference antibody, wherein the reference antibody comprises (a) a heavy chain CDR1 comprising GYSITSGYSLH (SEQ ID NO:79), a heavy chain CDR2 comprising YIHYSGSTNYNPSLKS (SEQ ID NO:80), and a heavy chain CDR3 comprising AWDYLDY (SEQ ID NO:81), and/or (b) a light chain CDR1 comprising RASENIYSQLA (SEQ ID NO:82), a light chain CDR2 comprising DAKTLAE (SEQ ID NO:83), and a light chain CDR3 comprising HHHFGILYT (SEQ ID NO:84). In some embodiments, an antibody competes for binding to C3 (e.g. human C3) with a reference antibody, wherein the reference antibody comprises (a) a heavy chain CDR1 comprising GYSITSGYYWN (SEQ ID NO:85), a heavy chain CDR2 comprising YIRYDGSNNYNPSLKN (SEQ ID NO:86), and a heavy chain CDR3 comprising HYGYDGGAFDF (SEQ ID NO:87), and/or (b) a light chain CDR1 comprising RTSENIYNYLV (SEQ ID NO:88), a light chain CDR2 comprising NAKTLEE (SEQ ID NO:89), and a light chain CDR3 comprising QHHYGTPFT (SEQ ID NO:90).

In some embodiments, an antibody competes for binding to C3 (e.g., human C3) with a reference antibody, wherein the reference antibody comprises: (a) a heavy chain variable region comprising SEQ ID NO:91 and (b) a light chain variable region comprising SEQ ID NO:92. In some embodiments, an antibody competes for binding to C3 (e.g., human C3) with a reference antibody, wherein the reference antibody comprises: (a) a heavy chain variable region comprising SEQ ID NO:93 and (b) a light chain variable region comprising SEQ ID NO:94. In some embodiments, an antibody competes for binding to C3 (e.g., human C3) with a reference antibody, wherein the reference antibody comprises: (a) a heavy chain variable region comprising SEQ ID NO:95 and (b) a light chain variable region comprising SEQ ID NO:96. In some embodiments, an antibody competes for binding to C3 (e.g., human C3) with a reference antibody, wherein the reference antibody comprises: (a) a heavy chain variable region comprising SEQ ID NO:97 and (b) a light chain variable region comprising SEQ ID NO:98. In some embodiments, an antibody competes for binding to C3 (e.g., human C3) with a reference antibody, wherein the reference antibody comprises: (a) a heavy chain variable region comprising SEQ ID NO:99 and (b) a light chain variable region comprising SEQ ID NO:100. In some embodiments, an antibody competes for binding to C3 (e.g., human C3) with a reference antibody, wherein the reference antibody comprises: (a) a heavy chain variable region comprising SEQ ID NO:101 and (b) a light chain variable region comprising SEQ ID NO:102. In some embodiments, an antibody competes for binding to C3 (e.g., human C3) with a reference antibody, wherein the reference antibody comprises: (a) a heavy chain variable region comprising SEQ ID NO:103 and (b) a light chain variable region comprising SEQ ID NO:104. In some embodiments, an antibody competes for binding to C3 (e.g., human C3) with a reference antibody, wherein the reference antibody comprises: (a) a heavy chain variable region comprising SEQ ID NO:105 and (b) a light chain variable region comprising SEQ ID NO:106. In some embodiments, an antibody competes for binding to C3 (e.g., human C3) with a reference antibody, wherein the reference antibody comprises: (a) a heavy chain variable region comprising SEQ ID NO:107 and (b) a light chain variable region comprising SEQ ID NO:108.

In some embodiments, a C3-binding agent described herein comprises an antibody in which at least one or more of the constant regions has been modified or deleted. In some embodiments, the antibodies may comprise modifications to one or more of the three heavy chain constant regions (CH1, CH2 or CH3) and/or to the light chain constant region (CL). In some embodiments, the heavy chain constant region of the modified antibodies comprises at least one human constant region. In some embodiments, the heavy chain constant region of the modified antibodies comprises more than one human constant region. In some embodiments, modifications to the constant region comprise additions, deletions, or substitutions of one or more amino acids in one or more regions. In some embodiments, one or more regions are partially or entirely deleted from the constant regions of the modified antibodies. In some embodiments, the entire CH2 domain has been removed from an antibody (ACH2 constructs). In some embodiments, a deleted constant region is replaced by a short amino acid spacer that provides some of the molecular flexibility typically imparted by the absent constant region. In some embodiments, a modified antibody comprises a CH3 domain directly fused to the hinge region of the antibody. In some embodiments, a modified antibody comprises a peptide spacer inserted between the hinge region and modified CH2 and/or CH3 domains.

It is known in the art that the constant region(s) of an antibody mediates several effector functions and these effector functions can vary depending on the isotype of the antibody. For example, binding of the C1 component of complement to the Fc region of IgG or IgM antibodies (bound to antigen) activates the complement system. Activation of complement is important in the opsonization and lysis of cell pathogens. The activation of complement also stimulates the inflammatory response and can be involved in autoimmune hypersensitivity. In addition, the Fc region of an antibody can bind a cell expressing a Fc receptor (FcR). There are a number of Fc receptors which are specific for different classes of antibody, including IgG (gamma receptors), IgE (epsilon receptors), IgA (alpha receptors) and IgM (mu receptors). Binding of antibody to Fc receptors on cell surfaces triggers a number of important and diverse biological responses including engulfment and destruction of antibody-coated particles, clearance of immune complexes, lysis of antibody-coated target cells by killer cells (called antibody-dependent cell cytotoxicity or ADCC), release of inflammatory mediators, placental transfer, and control of immunoglobulin production.

In some embodiments, an antibody comprises a variant Fc region. The amino acid sequences of the Fc region of human IgG1, IgG2, IgG3, and IgG4 are known to those of ordinary skill in the art (e.g., a representative human IgG1 is SEQ ID NO:34). In some cases, Fc regions with amino acid variations have been identified in native antibodies. In some embodiments, a variant Fc region is engineered with substitutions at specific amino acid positions as compared to a native Fc region (e.g., SEQ ID NO:35, SEQ ID NO:36, and SEQ ID NO:109).

In some embodiments, the modified antibodies (e.g., modified Fc region) provide for altered effector functions that, in turn, affect the biological profile of the antibody. For example, in some embodiments, the deletion or inactivation (through point mutations or other means) of a constant region reduces Fc receptor binding of the modified antibody as it circulates. In some embodiments, the constant region modifications increase the serum half-life of the antibody. In some embodiments, the constant region modifications reduce the serum half-life of the antibody. In some embodiments, the constant region modifications decrease or remove ADCC and/or complement dependent cytotoxicity (CDC) of the antibody. In some embodiments, specific amino acid substitutions in a human IgG1 Fc region with corresponding IgG2 or IgG4 residues reduce effector functions (e.g., ADCC and CDC) in the modified antibody. In some embodiments, an antibody does not have one or more effector functions (e.g., “effectorless” antibodies). In some embodiments, the antibody has no ADCC activity and/or no CDC activity. In some embodiments, the antibody does not bind an Fc receptor and/or complement factors. In some embodiments, the antibody has no effector function(s). In some embodiments, the constant region modifications increase or enhance ADCC and/or CDC of the antibody. In some embodiments, the constant region is modified to eliminate disulfide linkages or oligosaccharide moieties. In some embodiments, the constant region is modified to add/substitute one or more amino acids to provide one or more cytotoxin, oligosaccharide, or carbohydrate attachment sites.

In certain embodiments, a C3-binding agent comprises a heavy chain comprising heavy chain CDRs 1, 2, and 3, and a light chain comprising light chain CDRs 1, 2, and 3, wherein heavy chain CDR1 comprises GYTFTDFYMD (SEQ ID NO:7), heavy chain CDR2 comprises YIYPHNGGTTYNQNFTG (SEQ ID NO:8), heavy chain CDR3 comprises RGGFDFDY (SEQ ID NO:9), light chain CDR1 comprises KASENVDTYVS (SEQ ID NO:10), light chain CDR2 comprises GASNRYT (SEQ ID NO:11), and light chain CDR3 comprises GQSHSYPLT (SEQ ID NO:12), wherein the heavy chain comprises at least 80%, at least 85%, at least 90%, at least 95%, at least 97%, or 100% identity to the sequence set forth in SEQ ID NO:27, and wherein the light chain comprises at least 80%, at least 85%, at least 90%, at least 95%, at least 97%, or 100% identity to the sequence set forth in SEQ ID NO:31. In certain embodiments, a C3-binding agent comprises a heavy chain comprising heavy chain CDRs 1, 2, and 3, and a light chain comprising light chain CDRs 1, 2, and 3, wherein heavy chain CDR1 comprises GYTFTDFYMD (SEQ ID NO:7), heavy chain CDR2 comprises YIYPHNGGTTYNQQFTG (SEQ ID NO:13), heavy chain CDR3 comprises RGGFDFDY (SEQ ID NO:9), light chain CDR1 comprises KASENVDTYVS (SEQ ID NO:10), light chain CDR2 comprises GASNRYT (SEQ ID NO:11), and light chain CDR3 comprises GQSHSYPLT (SEQ ID NO:12), wherein the heavy chain comprises at least 80%, at least 85%, at least 90%, at least 95%, at least 97%, or 100% identity to the sequence set forth in SEQ ID NO:27, and wherein the light chain comprises at least 80%, at least 85%, at least 90%, at least 95%, at least 97%, or 100% identity to the sequence set forth in SEQ ID NO:31. In certain embodiments, a C3-binding agent comprises heavy chain CDRs 1, 2, and 3, and a light chain comprising light chain CDRs 1, 2, and 3, wherein heavy chain CDR1 comprises GYTFTDFYMD (SEQ ID NO:7), heavy chain CDR2 comprises YIYPHNAGTTYNQQFTG (SEQ ID NO:14), heavy chain CDR3 comprises RGGFDFDY (SEQ ID NO:9), light chain CDR1 comprises KASENVDTYVS (SEQ ID NO:10), light chain CDR2 comprises GASNRYT (SEQ ID NO:11), and light chain CDR3 comprises GQSHSYPLT (SEQ ID NO:12), wherein the heavy chain comprises at least 80%, at least 85%, at least 90%, at least 95%, at least 97%, or 100% identity to the sequence set forth in SEQ ID NO:29, and wherein the light chain comprises at least 80%, at least 85%, at least 90%, at least 95%, at least 97%, or 100% identity to the sequence set forth in SEQ ID NO:31. In certain embodiments, a C3-binding agent comprises a heavy chain comprising heavy chain CDRs 1, 2, and 3, and a light chain comprising light chain CDRs 1, 2, and 3, wherein heavy chain CDR1 comprises GYTFTDFYMD (SEQ ID NO:7), heavy chain CDR2 comprises YIYPHNTGTTYNQQFTG (SEQ ID NO:15), heavy chain CDR3 comprises RGGFDFDY (SEQ ID NO:9), light chain CDR1 comprises KASENVDTYVS (SEQ ID NO:10), light chain CDR2 comprises GASNRYT (SEQ ID NO:11), and light chain CDR3 comprises GQSHSYPLT (SEQ ID NO:12), wherein the heavy chain comprises at least 80%, at least 85%, at least 90%, at least 95%, or at least 97% identity to the sequence set forth in SEQ ID NO:27, and wherein the light chain comprises at least 80%, at least 85%, at least 90%, at least 95%, at least 97%, or 100% identity to the sequence set forth in SEQ ID NO:31. In certain embodiments, a C3-binding agent comprises a heavy chain comprising heavy chain CDRs 1, 2, and 3, and a light chain comprising light chain CDRs 1, 2, and 3, wherein heavy chain CDR1 comprises GYTFTDFYMD (SEQ ID NO:7), heavy chain CDR2 comprises YIYPHEGGTTYNQQFTG (SEQ ID NO:16), heavy chain CDR3 comprises RGGFDFDY (SEQ ID NO:9), light chain CDR1 comprises KASENVDTYVS (SEQ ID NO:10), light chain CDR2 comprises GASNRYT (SEQ ID NO:11), and light chain CDR3 comprises GQSHSYPLT (SEQ ID NO:12), wherein the heavy chain comprises at least 80%, at least 85%, at least 90%, at least 95%, or at least 97% identity to the sequence set forth in SEQ ID NO:27, and wherein the light chain comprises at least 80%, at least 85%, at least 90%, at least 95%, at least 97%, or 100% identity to the sequence set forth in SEQ ID NO:31. In certain embodiments, a C3-binding agent comprises a heavy chain comprising heavy chain CDRs 1, 2, and 3, and a light chain comprising light chain CDRs 1, 2, and 3, wherein heavy chain CDR1 comprises GYTFTDFYMD (SEQ ID NO:7), heavy chain CDR2 comprises YIYPHQGGTTYNQQFTG (SEQ ID NO:17), heavy chain CDR3 comprises RGGFDFDY (SEQ ID NO:9), light chain CDR1 comprises KASENVDTYVS (SEQ ID NO:10), light chain CDR2 comprises GASNRYT (SEQ ID NO:11), and light chain CDR3 comprises GQSHSYPLT (SEQ ID NO:12), wherein the heavy chain comprises at least 80%, at least 85%, at least 90%, at least 95%, at least 97%, or 100% identity to the sequence set forth in SEQ ID NO:27, and wherein the light chain comprises at least 80%, at least 85%, at least 90%, at least 95%, at least 97%, or 100% identity to the sequence set forth in SEQ ID NO:31.

In some embodiments, a C3-binding agent is an antibody that comprises a heavy chain of SEQ ID NO:27 and/or a light chain of SEQ ID NO:31. In some embodiments, a C3-binding agent is an antibody that comprises a heavy chain of SEQ ID NO:27. In some embodiments, a C3-binding agent is an antibody that comprises a light chain of SEQ ID NO:31. In some embodiments, a C3-binding agent is an antibody that comprises a heavy chain of SEQ ID NO:27 and a light chain of SEQ ID NO:31. In some embodiments, a C3-binding agent is an antibody that comprises a heavy chain of SEQ ID NO:29 and/or a light chain of SEQ ID NO:31. In some embodiments, a C3-binding agent is an antibody that comprises a heavy chain of SEQ ID NO:29. In some embodiments, a C3-binding agent is an antibody that comprises a light chain of SEQ ID NO:31. In some embodiments, a C3-binding agent is an antibody that comprises a heavy chain of SEQ ID NO:29 and a light chain of SEQ ID NO:31.

Modifications to the constant region of antibodies described herein may be made using well known biochemical or molecular engineering techniques. In some embodiments, antibody variants are prepared by introducing appropriate nucleotide changes into the encoding DNA, and/or by synthesis of the desired antibody or polypeptide. Using these antibody variants it may be possible to disrupt the activity or effector function provided by a specific sequence or region while substantially maintaining the structure, binding activity, and other desired characteristics of the modified antibody.

The present disclosure further embraces additional variants and equivalents that are substantially homologous to the recombinant, monoclonal, chimeric, humanized, and human antibodies, or antibody fragments thereof, described herein. In some embodiments, it is desirable to improve the binding affinity of the antibody. In some embodiments, it is desirable to modulate biological properties of the antibody, including but not limited to, specificity, thermostability, expression level, effector function(s), glycosylation, immunogenicity, or solubility. Those skilled in the art will appreciate that amino acid changes may alter post-translational processes of an antibody, such as changing the number or position of glycosylation sites or altering membrane anchoring characteristics.

Variations may be a substitution, deletion, or insertion of one or more nucleotides encoding the antibody or polypeptide that results in a change in the amino acid sequence as compared with the native antibody or polypeptide sequence. In some embodiments, amino acid substitutions are the result of replacing one amino acid with another amino acid having similar structural and/or chemical properties, such as the replacement of a leucine with a serine, e.g., conservative amino acid replacements. Insertions or deletions may optionally be in the range of about 1 to 5 amino acids. In some embodiments, the substitution, deletion, or insertion includes less than 25 amino acid substitutions, less than 20 amino acid substitutions, less than 15 amino acid substitutions, less than 10 amino acid substitutions, less than 5 amino acid substitutions, less than 4 amino acid substitutions, less than 3 amino acid substitutions, or less than 2 amino acid substitutions relative to the parent molecule. In some embodiments, variations in the amino acid sequence that are biologically useful and/or relevant are determined by systematically making insertions, deletions, or substitutions in the sequence and testing the resulting variant proteins for activity as compared to the parental antibody.

In some embodiments, variants may include addition of amino acid residues at the amino- and/or carboxyl-terminal end of the antibody or polypeptide. The length of additional amino acids residues may range from one residue to a hundred or more residues. In some embodiments, a variant comprises an N-terminal methionyl residue. In some embodiments, the variant comprises an additional polypeptide/protein, i.e., a fusion protein. In some embodiments, a variant is engineered to be detectable and may comprise a detectable label and/or protein (e.g., an enzyme).

In some embodiments, a cysteine residue not involved in maintaining the proper conformation of an antibody may be substituted or deleted to modulate the antibody's characteristics, for example, to improve oxidative stability and/or prevent aberrant disulfide crosslinking. Conversely, in some embodiments, one or more cysteine residues may be added to create disulfide bond(s) to improve stability.

In some embodiments, an antibody of the present disclosure is “deimmunized”. The deimmunization of antibodies generally consists of introducing specific amino acid mutations (e.g, substitutions, deletions, additions) that result in removal of T-cell epitopes without significantly reducing the binding affinity or other desired activities of the antibody.

The variant antibodies or polypeptides described herein may be generated using methods known in the art, including but not limited to, site-directed mutagenesis, alanine scanning mutagenesis, and PCR mutagenesis.

In some embodiments, C3-binding agents described herein are chemically modified. In some embodiments, the C3-binding agents are anti-C3 antibodies that have been chemically modified by glycosylation, acetylation, pegylation, phosphorylation, amidation, derivatization by known protecting/blocking groups, proteolytic cleavage, and/or linkage to a cellular ligand or other protein. Any of numerous chemical modifications may be carried out by known techniques.

The present disclosure encompasses C3-binding agents built upon non-immunoglobulin backbones, wherein the agents bind to the same epitope or essentially the same epitope as an anti-C3 antibody disclosed herein. In some embodiments, a non-immunoglobulin-based binding agent is an agent that competes with an anti-C3 antibody described herein in a competitive binding assay. In some embodiments, alternative C3-binding agents comprise a scaffold protein. Generally, scaffold proteins can be assigned to one of three groups based on the architecture of their backbone (1) scaffolds consisting of α-helices; (2) small scaffolds with few secondary structures or an irregular architecture of α-helices and β-sheets; and (3) scaffolds consisting of predominantly β-sheets. Scaffold proteins include, but are not limited to, anticalins, which are based upon the lipocalin scaffold; adnectins, which are based on the 10^(th) domain of human fibronectin type 3; affibodies, which are based on the B-domain in the Ig-binding region of Staphylococcus aureus protein A; darpins, which are based on ankyrin repeat domain proteins; fynomers, which are based on the SH3 domain of the human Fyn protein kinase; affitins, which are based on Sac7d from Sulfolobus acidocaldarius; affilins, which are based on human γ-B-crystallin or human ubiquitin; avimers, which are based on the A-domains of membrane receptor proteins; knottins (cysteine knot miniproteins), which are based upon a stable 30-amino acid anti-parallel β-strand protein fold; and Kunitz domain inhibitor scaffolds, which are based upon a structure that contains three disulfide bonds and three loops. In some embodiments, a C3-binding agent comprises an engineered scaffold protein comprising a heavy chain CDR1, CDR2, and CDR3 and a light chain CDR1, CDR2, and CDR3 shown in Table 1. In some embodiments, a C3-binding agent comprises an engineered scaffold protein comprising a heavy chain CDR1 comprising GYTFTDFYMD (SEQ ID NO:7), a heavy chain CDR2 comprising YIYPHNGGTTYNQNFTG (SEQ ID NO:8), YIYPHNGGTTYNQQFTG (SEQ ID NO:13), YIYPHNAGTTYNQQFTG (SEQ ID NO:14), YIYPHNTGTTYNQQFTG (SEQ ID NO:15), YIYPHEGGTTYNQQFTG (SEQ ID NO:16), or YIYPHQGGTTYNQQFTG (SEQ ID NO: 17), and a heavy chain CDR3 comprising RGGFDFDY (SEQ ID NO:9); and/or (b) a light chain variable region comprising a light chain CDR1 comprising KASENVDTYVS (SEQ ID NO:10), a light chain CDR2 comprising GASNRYT (SEQ ID NO:11), and a light chain CDR3 comprising GQSHSYPLT (SEQ ID NO:12).

In some embodiments, a C3-binding agent comprises an engineered scaffold protein comprising a heavy chain CDR1, CDR2, and CDR3 and a light chain CDR1, CDR2, and CDR3 from antibody 3D8. In some embodiments, a C3-binding agent comprises an engineered scaffold protein comprising a heavy chain CDR1, CDR2, and CDR3 and a light chain CDR1, CDR2, and CDR3 from antibody 3G8. In some embodiments, a C3-binding agent comprises an engineered scaffold protein comprising a heavy chain CDR1, CDR2, and CDR3 and a light chain CDR1, CDR2, and CDR3 from antibody 15C12. In some embodiments, a C3-binding agent comprises an engineered scaffold protein comprising a heavy chain CDR1, CDR2, and CDR3 and a light chain CDR1, CDR2, and CDR3 from antibody 27A8. In some embodiments, a C3-binding agent comprises an engineered scaffold protein comprising a heavy chain CDR1, CDR2, and CDR3 and a light chain CDR1, CDR2, and CDR3 from antibody 28C3. In some embodiments, a C3-binding agent comprises an engineered scaffold protein comprising a heavy chain CDR1, CDR2, and CDR3 and a light chain CDR1, CDR2, and CDR3 from antibody 38F5. In some embodiments, a C3-binding agent comprises an engineered scaffold protein comprising a heavy chain CDR1, CDR2, and CDR3 and a light chain CDR1, CDR2, and CDR3 from antibody 62B11. In some embodiments, a C3-binding agent comprises an engineered scaffold protein comprising a heavy chain CDR1, CDR2, and CDR3 and a light chain CDR1, CDR2, and CDR3 from antibody 62F2. In some embodiments, a C3-binding agent comprises an engineered scaffold protein comprising a heavy chain CDR1, CDR2, and CDR3 and a light chain CDR1, CDR2, and CDR3 from antibody 63A3.

Generally speaking, antigen-antibody interactions are non-covalent and reversible, formed by a combination of hydrogen bonds, hydrophobic interactions, electrostatic and van der Waals forces. When describing the strength of an antigen-antibody complex, the terms affinity and/or avidity are commonly used mentioned. The binding of an antibody to its antigen is a reversible process, and the affinity of the binding is typically reported as an equilibrium dissociation constant (K_(D)). K_(D) is the ratio of an antibody dissociation rate (k_(off)) (how quickly it dissociates from its antigen) to the antibody association rate (k_(on)) (how quickly it binds to its antigen). In some embodiments, K_(D) values are determined by measuring the k_(on) and k_(off) rates of a specific antibody/antigen interaction and then using a ratio of these values to calculate the K_(D) value. K_(D) values may be used to evaluate and rank order the strength of individual antibody/antigen interactions. The lower the K_(D) of an antibody, the higher the affinity of the antibody for its target. In some embodiments, affinity is measured using SPR technology in a Biacore system. Avidity gives a measure of the overall strength of an antibody-antigen complex. It is dependent on three major parameters: (i) affinity of the antibody for the target, (ii) valency of both the antibody and antigen, and (iii) structural arrangement of the parts that interact.

In some embodiments, a C3-binding agent (e.g., an antibody) binds C3 (e.g., human C3) with a dissociation constant (K_(D)) of about 1 μM or less, about 100 nM or less, about 40 nM or less, about 20 nM or less, about 10 nM or less, about 1 nM or less, about 0.1 nM or less, 50 pM or less, 10 pM or less, or 1 pM or less. In some embodiments, a C3-binding agent binds C3 (e.g., human C3) with a K_(D) of about 20 nM or less. In some embodiments, a C3-binding agent binds C3 (e.g., human C3) with a K_(D) of about 10 nM or less. In some embodiments, a C3-binding agent binds C3 (e.g., human C3) with a K_(D) of about 1 nM or less. In some embodiments, a C3-binding agent binds C3 (e.g., human C3) with a K_(D) of about 0.5 nM or less. In some embodiments, a C3-binding agent binds C3 (e.g., human C3) with a K_(D) of about 0.1 nM or less. In some embodiments, a C3-binding agent binds C3 (e.g., human C3) with a K_(D) of about 50 pM or less. In some embodiments, a C3-binding agent binds C3 (e.g., human C3) with a K_(D) of about 25 pM or less. In some embodiments, a C3-binding agent binds C3 (e.g., human C3) with a K_(D) of about 10 pM or less. In some embodiments, a C3-binding agent binds C3 (e.g., human C3) with a K_(D) of about 1 pM or less. In some embodiments, the dissociation constant of the binding agent (e.g., an antibody) for C3 is the dissociation constant determined using a C3 protein immobilized on a Biacore chip and the binding agent flowed over the chip. In some embodiments, the dissociation constant of the binding agent (e.g., an antibody) for C3 is the dissociation constant determined using the binding agent captured by an anti-human IgG antibody on a Biacore chip and soluble C3 flowed over the chip.

In some embodiments, a C3-binding agent (e.g., an antibody) binds C3 (e.g., human C3) with a half maximal effective concentration (EC50) of about 1 μM or less, about 100 nM or less, about 40 nM or less, about 20 nM or less, about 10 nM or less, about 1 nM or less, or about 0.1 nM or less. In some embodiments, a C3-binding agent binds to human C3 with an EC50 of about 1 μM or less, about 100 nM or less, about 40 nM or less, about 20 nM or less, about 10 nM or less, about 1 nM or less, or about 0.1 nM or less. In some embodiments, a C3-binding agent binds cyno C3 and/or human C3 with an EC50 of about 40 nM or less, about 20 nM or less, about 10 nM or less, about 1 nM or less or about 0.1 nM or less.

The C3-binding agents (e.g., antibodies) described herein can be produced by any suitable method known in the art. Such methods range from direct protein synthesis methods to constructing a DNA sequence encoding polypeptide sequences and expressing those sequences in a suitable host. In some embodiments, a DNA sequence is constructed using recombinant technology by isolating or synthesizing a DNA sequence encoding a wild-type protein of interest. Optionally, the sequence can be mutagenized by site-specific mutagenesis to provide functional variants thereof. In some embodiments, a DNA sequence encoding a polypeptide of interest is constructed by chemical synthesis using an oligonucleotide synthesizer. Oligonucleotides can be designed based on the amino acid sequence of the desired polypeptide and selecting those codons that are favored in the host cell in which the recombinant polypeptide of interest will be produced. Standard methods can be applied to synthesize a polynucleotide sequence encoding an isolated polypeptide of interest. For example, a complete amino acid sequence can be used to construct a back-translated gene. Further, a DNA oligomer containing a nucleotide sequence coding for the particular isolated polypeptide can be synthesized. For example, several small oligonucleotides coding for portions of the desired polypeptide can be synthesized and then ligated. The individual oligonucleotides typically contain 5′ or 3′ overhangs for complementary assembly.

Once assembled (by synthesis, site-directed mutagenesis, or another method), the polynucleotide sequences encoding a particular polypeptide of interest can be inserted into an expression vector and operatively linked to an expression control sequence appropriate for expression of the protein in a desired host. Proper assembly can be confirmed by nucleotide sequencing, restriction enzyme mapping, and/or expression of a biologically active polypeptide in a suitable host. As is well-known in the art, in order to obtain high expression levels of a transfected gene in a host, the gene must be operatively linked to transcriptional and translational expression control sequences that are functional in the chosen expression host.

In some embodiments, recombinant expression vectors are used to amplify and express DNA encoding antibodies, or fragments thereof, against human C3. For example, recombinant expression vectors can be replicable DNA constructs which have synthetic or cDNA-derived DNA fragments encoding a polypeptide chain of a C3-binding agent, such as an anti-C3 antibody, or antigen-binding fragment thereof, operatively linked to suitable transcriptional and/or translational regulatory elements derived from mammalian, microbial, viral or insect genes. A transcriptional unit generally comprises an assembly of (1) a genetic element or elements having a regulatory role in gene expression, for example, transcriptional promoters or enhancers, (2) a structural or coding sequence which is transcribed into mRNA and translated into protein, and (3) appropriate transcription and translation initiation and termination sequences. Regulatory elements can include an operator sequence to control transcription. The ability to replicate in a host, usually conferred by an origin of replication, and a selection gene to facilitate recognition of transformants can additionally be incorporated. DNA regions are “operatively linked” when they are functionally related to each other. For example, DNA for a signal peptide (secretory leader) is operatively linked to DNA for a polypeptide if it is expressed as a precursor which participates in the secretion of the polypeptide; a promoter is operatively linked to a coding sequence if it controls the transcription of the sequence; or a ribosome binding site is operatively linked to a coding sequence if it is positioned so as to permit translation. In some embodiments, structural elements intended for use in yeast expression systems include a leader sequence enabling extracellular secretion of translated protein by a host cell. In some embodiments, in situations where recombinant protein is expressed without a leader or transport sequence, a polypeptide may include an N-terminal methionine residue. This residue can optionally be subsequently cleaved from the expressed recombinant protein to provide a final product.

The choice of an expression control sequence and an expression vector generally depends upon the choice of host. A wide variety of expression host/vector combinations can be employed. Useful expression vectors for eukaryotic hosts include, for example, vectors comprising expression control sequences from SV40, bovine papilloma virus, adenovirus, and cytomegalovirus. Useful expression vectors for bacterial hosts include known bacterial plasmids, such as plasmids from E. coli, including pCR1, pBR322, pMB9 and their derivatives, and wider host range plasmids, such as M13 and other filamentous single-stranded DNA phages.

The C3-binding agents (e.g., antibodies) of the present disclosure can be expressed from one or more vectors. For example, in some embodiments, a heavy chain polypeptide is expressed by one vector and a light chain polypeptide is expressed by a second vector. In some embodiments, a heavy chain polypeptide and a light chain polypeptide are expressed by one vector.

Suitable host cells for expression of a C3-binding agent (e.g., an antibody) or a C3 protein or fragment thereof to use as an antigen or immunogen include prokaryotes, yeast cells, insect cells, or higher eukaryotic cells under the control of appropriate promoters. Prokaryotes include gram-negative or gram-positive organisms, for example E. coli or Bacillus. Higher eukaryotic cells include established cell lines of mammalian origin as described herein. Cell-free translation systems may also be employed. Appropriate cloning and expression vectors for use with bacterial, fungal, yeast, and mammalian cellular hosts, as well as methods of protein production, including antibody production are well known in the art.

Various mammalian culture systems may be used to express recombinant polypeptides. Expression of recombinant proteins in mammalian cells may be desirable because these proteins are generally correctly folded, appropriately modified, and biologically functional. Examples of suitable mammalian host cell lines include, but are not limited to, COS-7 (monkey kidney-derived), L-929 (murine fibroblast-derived), C127 (murine mammary tumor-derived), 3T3 (murine fibroblast-derived), CHO (Chinese hamster ovary-derived), HeLa (human cervical cancer-derived), BHK (hamster kidney fibroblast-derived), HEK-293 (human embryonic kidney-derived) cell lines and variants thereof. Mammalian expression vectors can comprise non-transcribed elements such as an origin of replication, a suitable promoter and enhancer linked to the gene to be expressed, and other 5′ or 3′ flanking non-transcribed sequences, and 5′ or 3′ non-translated sequences, such as necessary ribosome binding sites, a polyadenylation site, splice donor and acceptor sites, and transcriptional termination sequences.

Expression of recombinant proteins in insect cell culture systems (e.g., baculovirus) also offers a robust method for producing correctly folded and biologically functional proteins. Baculovirus systems for production of heterologous proteins in insect cells are well-known to those of skill in the art.

Thus, the present disclosure provides cells comprising the C3-binding agents described herein. In some embodiments, the cells produce the C3-binding agents described herein. In some embodiments, the cells produce an antibody. In some embodiments, the cells produce an antibody that binds human C3. In some embodiments, the cells produce an antibody that binds cyno C3. In some embodiments, the cells produce an antibody that binds human C3 and cyno C3. In some embodiments, the cells produce an antibody designated 38G10. In some embodiments, the cells produce a humanized version of antibody 38G10, referred to as Hz38G10. In some embodiments, the cells produce a variant of Hz38G10, for example, Hz38G10(G56A), Hz38G10(G56T), Hz38G10(N55E), or Hz38G10(N55Q). In some embodiments, the cells produce antibody Hz38G10(G56A). In some embodiments, the cells produce a scFv version of antibody Hz38G10, referred to as dsscFv Hz38G10. In some embodiments, the cells produce a scFv version of antibody Hz38G10(G56A), referred to as dsscFv Hz38G10(G56A). In some embodiments, the cells produce an antibody designated 3D8. In some embodiments, the cells produce a humanized version of antibody 3D8. In some embodiments, the cells produce an antibody designated 3G8. In some embodiments, the cells produce a humanized version of antibody 3G8. In some embodiments, the cells produce an antibody designated 15C12. In some embodiments, the cells produce a humanized version of antibody 15C12. In some embodiments, the cells produce an antibody designated 27A8. In some embodiments, the cells produce a humanized version of antibody 27A8. In some embodiments, the cells produce an antibody designated 28C3. In some embodiments, the cells produce a humanized version of antibody 28C3. In some embodiments, the cells produce an antibody designated 38F5. In some embodiments, the cells produce a humanized version of antibody 38F5. In some embodiments, the cells produce an antibody designated 62B11. In some embodiments, the cells produce a humanized version of antibody 62B11. In some embodiments, the cells produce an antibody designated 62F2. In some embodiments, the cells produce a humanized version of antibody 62F2. In some embodiments, the cells produce an antibody designated 63A3. In some embodiments, the cells produce a humanized version of antibody 63A3. In some embodiments, the cell is a prokaryotic cell (e.g., E. coli). In some embodiments, the cell is an eukaryotic cell. In some embodiments, the cell is a mammalian cell. In some embodiments, the cell is a hybridoma cell.

Proteins produced by a host cell can be purified according to any suitable method. Standard methods include chromatography (e.g., ion exchange, affinity, and sizing column chromatography), centrifugation, differential solubility, or by any other standard technique for protein purification. Affinity tags such as hexa-histidine (SEQ ID NO:231), maltose binding domain, influenza coat sequence, and glutathione-S-transferase can be attached to the protein to allow easy purification by passage over an appropriate affinity column. Affinity chromatography used for purifying immunoglobulins can include Protein A, Protein G, and Protein L chromatography. Isolated proteins can be physically characterized using such techniques as proteolysis, size exclusion chromatography (SEC), mass spectrometry (MS), nuclear magnetic resonance (NMR), isoelectric focusing (IEF), high performance liquid chromatography (HPLC), and x-ray crystallography. The purity of isolated proteins can be determined using techniques known to those of skill in the art, including but not limited to, SDS-PAGE, SEC, capillary gel electrophoresis, IEF, and capillary isoelectric focusing (cIEF).

In some embodiments, supernatants from expression systems which secrete recombinant protein into culture media are first concentrated using a commercially available protein concentration filter, for example, an Amicon® or Millipore Pellicon® ultrafiltration unit. Following the concentration step, the concentrate can be applied to a suitable purification matrix. In some embodiments, an anion exchange resin is employed, for example, a matrix or substrate having pendant diethylaminoethyl (DEAE) groups. The matrices can be acrylamide, agarose, dextran, cellulose, or other types commonly employed in protein purification. In some embodiments, a cation exchange step is employed. Suitable cation exchangers include various insoluble matrices comprising sulfopropyl or carboxymethyl groups. In some embodiments, a hydroxyapatite media is employed, including but not limited to, ceramic hydroxyapatite (CHT). In some embodiments, one or more reverse-phase HPLC steps employing hydrophobic RP-HPLC media, e.g., silica gel having pendant methyl or other aliphatic groups, are employed to further purify a recombinant protein. In some embodiments, hydrophobic interaction chromatography (HIC) is used to separate recombinant proteins based on their hydrophobicity. HIC is a useful separation technique for purifying proteins while maintaining biological activity due to the use of conditions and matrices that operate under less denaturing conditions than some other techniques. Some or all of the foregoing purification steps, in various combinations, can be employed to provide a homogeneous recombinant protein.

Anti-C3 antibodies of the present disclosure may be analyzed for their physical/chemical properties and/or biological activities by various assays known in the art. In some embodiments, an anti-C3 antibody is tested for its ability to bind C3 (e.g., human C3 and/or cyno C3). Binding assays include, but are not limited to, SPR (e.g., Biacore), ELISA, and FACS. In some embodiments, an anti-C3 antibody is tested for its ability to inhibit, reduce, or block complement and/or C3 activity. Assays include, but are not limited to, hemolysis assays and C3a release assays. In addition, antibodies may be evaluated for solubility, stability, thermostability, viscosity, expression levels, expression quality, and/or purification efficiency.

In some embodiments, monoclonal antibodies generated against C3 are grouped based upon the epitope each individual antibody recognizes, a process known as “epitope binning”. Generally, antibodies are tested in a pairwise combinatorial manner and antibodies that compete with each other are grouped together into bins. For example, in a premix binning assay, a first antibody is immobilized on a surface and a premixed solution of a second antibody and antigen is flowed over the immobilized first antibody. In tandem, the antigen is immobilized on a surface and the two antibodies are flowed over the immobilized antigen and compete to bind. Using these techniques, antibodies that block one another can be identified. A competitive blocking profile is created for each antibody relative to the other antibodies. The blocking results determine which bin each antibody is placed in. High-throughput methods of epitope binning are known in the art and allow for screening and characterization of large numbers of antibodies within a short period of time. Antibodies that bind similar epitopes often share similar functions and/or capabilities. Conversely, antibodies that bind different epitopes may have different functional activities.

Epitope mapping is the process of identifying the binding site, or epitope on a target protein/antigen where an antibody (or other binding agent) binds. A variety of methods are known in the art for mapping epitopes on target proteins. These methods include mutagenesis, including but not limited to, shotgun mutagenesis, site-directed mutagenesis, and alanine scanning; domain or fragment scanning, peptide scanning (e.g., Pepscan technology); display methods (e.g., phage display, microbial display, and ribosome/mRNA display); methods involving proteolysis and mass spectroscopy; and structural determination (e.g., x-ray crystallography and NMR).

In some embodiments, purified anti-C3 antibodies are characterized by assays including, but not limited to, N-terminal sequencing, amino acid analysis, high pressure liquid chromatography (HPLC), mass spectrometry, ion exchange chromatography, and papain digestion.

In some embodiments, assays are provided for identifying anti-C3 antibodies that affect C3 activity. In some embodiments, hemolysis assays are used to assess the functional activity of the complement system. Hemolysis assays have been modified over the years to assess the activity of the different complement pathways and/or individual complement components of the cascade. In some embodiments, a hemolysis assay is used to assess activity of the alternative pathway. In some embodiments, a hemolysis assay is used to assess activity of the classical pathway.

In some embodiments, a C3-binding agent (e.g., an antibody) binds C3 and inhibits C3 activation of the alternative pathway. In some embodiments, a C3-binding agent (e.g., an antibody) binds C3 and inhibits activation of the alternative pathway, wherein the inhibition is evaluated by a hemolysis assay. In certain embodiments, the C3-binding agent (e.g., an antibody) inhibits activation of the alternative pathway by at least about 10%, at least about 20%, at least about 30%, at least about 50%, at least about 75%, at least about 90%, or about 100%. In some embodiments, percent inhibition is used to calculate an IC₅₀ (half maximal inhibitory concentration) for the C3-binding agent. In some embodiments, a C3-binding agent that inhibits activation of the alternative pathway is antibody 38G10, antibody Hz38G10, antibody Hz38G10(G56A), antibody Hz38G10(G56T), antibody Hz38G10(N55E), antibody Hz38G10(N55Q), antibody 3D8, antibody 3G8, antibody 15C12, antibody 27A8, antibody 28C3, antibody 38F5, antibody 62B11, antibody 62F2, or antibody 63A3. In some embodiments, a C3-binding agent that inhibits activation of the alternative pathway is antibody 38G10, antibody Hz38G10, or antibody Hz38G10(G56A). In some embodiments, a C3-binding agent that inhibits activation of the alternative pathway is dsscFv Hz38G10, or dsscFv Hz38G10(G56A).

In some embodiments, a C3-binding agent (e.g., an antibody) described herein binds C3 and inhibits C3 activation of the classical pathway. In some embodiments, a C3-binding agent (e.g., an antibody) binds C3 and inhibits activation of the classical pathway, wherein the inhibition is evaluated by a hemolysis assay. In certain embodiments, the C3-binding agent (e.g., an antibody) inhibits activation of the classical pathway by at least about 10%, at least about 20%, at least about 30%, at least about 50%, at least about 75%, at least about 90%, or about 100%. In some embodiments, a C3-binding agent that inhibits activation of the classical pathway is antibody 38G10, antibody Hz38G10, antibody Hz38G10(G56A), antibody Hz38G10(G56T), antibody Hz38G10(N55E), antibody Hz38G10(N55Q), antibody 3D8, antibody 3G8, antibody 15C12, antibody 27A8, antibody 28C3, antibody 38F5, antibody 62B11, antibody 62F2, or antibody 63A3. In some embodiments, a C3-binding agent that inhibits activation of the classical pathway is antibody 38G10, antibody Hz38G10, or antibody Hz38G10(G56A). In some embodiments, a C3-binding agent that inhibits activation of the classical pathway is dsscFv Hz38G10, or dsscFv Hz38G10(G56A).

In some embodiments, a C3-binding agent (e.g., an antibody) described herein binds C3 and inhibits C3 activation of the classical and alternative pathways. In some embodiments, a C3-binding agent (e.g., an antibody) binds C3 and inhibits activation of the classical and alternative pathways, wherein the inhibition is evaluated by a hemolysis assay. In certain embodiments, the C3-binding agent (e.g., an antibody) inhibits activation of the classical and alternative pathways by at least about 10%, at least about 20%, at least about 30%, at least about 50%, at least about 75%, at least about 90%, or about 100%. In some embodiments, a C3-binding agent that inhibits activation of the classical and alternative pathway is antibody 38G10, antibody Hz38G10, antibody Hz38G10(G56A), antibody Hz38G10(G56T), antibody Hz38G10(N55E), antibody Hz38G10(N55Q), antibody 3D8, antibody 3G8, antibody 15C12, antibody 27A8, antibody 28C3, antibody 38F5, antibody 62B11, antibody 62F2, or antibody 63A3. In some embodiments, a C3-binding agent that inhibits activation of the classical and alternative pathways is antibody 38G10, antibody Hz38G10, or antibody Hz38G10(G56A). In some embodiments, a C3-binding agent that inhibits activation of the classical and alternative pathways is dsscFv Hz38G10, or dsscFv Hz38G10(G56A).

In some embodiments, an immunochemical assay to determine the presence and/or amount of individual components (e.g., C3a) is used to assess the complement cascade. In some embodiments, a C3-binding agent (e.g., an antibody) described herein binds C3 and inhibits the release of C3a.

The present disclosure also provides conjugates comprising an anti-C3 antibody described herein. In some embodiments, the antibody is attached to a second molecule. In some embodiments, the antibody is conjugated to a cytotoxic agent or moiety. In some embodiments, the antibody is conjugated to a cytotoxic agent to form an ADC (antibody-drug conjugate). In some embodiments, the cytotoxic agent is a chemotherapeutic agent including, but not limited to, methotrexate, adriamycin/doxorubicin, melphalan, mitomycin C, chlorambucil, duocarmycin, daunorubicin, pyrrolobenzodiazepines (PBDs), or other intercalating agents. In some embodiments, the cytotoxic agent is a microtubule inhibitor including, but not limited to, auristatins, maytansinoids (e.g., DM1 and DM4), and tubulysins. In some embodiments, the cytotoxic agent is an enzymatically active toxin of bacterial, fungal, plant, or animal origin, or fragments thereof, including, but not limited to, diphtheria A chain, non-binding active fragments of diphtheria toxin, exotoxin A chain, ricin A chain, abrin A chain, modeccin A chain, alpha-sarcin, Aleurites fordii proteins, dianthin proteins, Phytolaca americana proteins (PAPI, PAPII, and PAP-S), Momordica charantia inhibitor, curcin, crotin, Sapaonaria officinalis inhibitor, gelonin, mitogellin, restrictocin, phenomycin, enomycin, and the tricothecenes. In some embodiments, an antibody is conjugated to one or more small molecule toxins, such as calicheamicins, maytansinoids, trichothenes, and CC1065. A derivative of any one of these toxins may be used as long as the derivative retains the cytotoxic activity of the parent molecule.

Conjugates comprising an anti-C3 antibody described herein may be made using any suitable method known in the art. In some embodiments, conjugates are made using a variety of bifunctional protein-coupling agents such as N-succinimidyl-3-(2-pyridyidithiol) propionate (SPDP), iminothiolane (IT), bifunctional derivatives of imidoesters (such as dimethyl adipimidate HCl), active esters (such as disuccinimidyl suberate), aldehydes (such as glutaraldehyde), bis-azido compounds (such as bis(p-azidobenzoyl) hexanediamine), bis-diazonium derivatives (such as bis-(p-diazoniumbenzoyl)-ethylenediamine), diisocyanates (such as toluene 2,6-diisocyanate), and bis-active fluorine compounds (such as 1,5-difluoro-2,4-dinitrobenzene).

In some embodiments, an anti-C3 antibody described herein is conjugated to a detectable substance or molecule that allows the antibody to be used for diagnosis and/or detection. A detectable substance can include but is not limited to, enzymes, such as horseradish peroxidase, alkaline phosphatase, beta-galactosidase, and acetylcholinesterase; prosthetic groups, such as biotin and flavine(s); fluorescent materials, such as, umbelliferone, fluorescein, fluorescein isothiocyanate (FITC), rhodamine, tetramethylrhodamine isothiocyanate (TRITC), dichlorotriazinylamine fluorescein, dansyl chloride, cyanine (Cy3), and phycoerythrin; bioluminescent materials, such as luciferase; radioactive materials, such as ²¹²Bi, ¹⁴C, ⁵⁷Co, ⁵¹Cr, ⁶⁷Cu, ¹⁸F, ⁶⁸Ga, ⁶⁷Ga, ¹⁵³Gd, ¹⁵⁹Gd, ⁶⁸Ge, ³H, ¹⁶⁶Ho, ¹³¹I, ¹²⁵I, ¹²³I, ¹²¹I, 115In, 113In, ¹¹²In, ¹¹¹In, ¹⁴⁰La, ¹⁷⁷Lu, ⁵⁴Mn, ⁹⁹Mo, ³²P, ¹⁰³Pd, ¹⁴⁹Pm, ¹⁴²Pr, ¹⁸⁶Re, ¹⁸⁸Re, ¹⁰⁵Rh, ⁹⁷Ru, 35S, ⁴⁷Sc, ⁷⁵Se, ¹⁵³Sm, ¹¹³Sn, ¹¹⁷Sn, ⁸⁵Sr, ^(99m)Tc, ²⁰¹Ti, ¹³³Xe, ⁹⁰Y, ⁶⁹Yb, ¹⁷⁵Yb, ⁶⁵Zn; positron emitting metals; and magnetic metal ions.

An anti-C3 antibody described herein can also be conjugated to a second antibody to form an antibody heteroconjugate.

An anti-C3 antibody as described herein may be attached to a solid support. Such solid supports include, but are not limited to, glass, cellulose, polyacrylamide, nylon, polystyrene, polyvinyl chloride, or polypropylene. In some embodiments, immobilized anti-C3 antibodies are used in immunoassays. In some embodiments, immobilized anti-C3 antibodies are used in purification of the target antigen.

III. Polynucleotides

In some embodiments, the disclosure encompasses polynucleotides comprising polynucleotides that encode a polypeptide (i.e., a C3-binding agent) described herein. The term “polynucleotides that encode a polypeptide” encompasses a polynucleotide which includes only coding sequences for the polypeptide as well as a polynucleotide which includes additional coding and/or non-coding sequences. The polynucleotides of the disclosure can be in the form of RNA or in the form of DNA. DNA includes cDNA, genomic DNA, and synthetic DNA; and can be double-stranded or single-stranded, and if single stranded can be the coding strand or non-coding (anti-sense) strand.

In some embodiments, the polynucleotide comprises a polynucleotide (e.g., a nucleotide sequence) encoding a polypeptide comprising an amino acid sequence selected from the group consisting of: SEQ ID NOs:18-31, 91-108, 110-114, 119, and 229. In some embodiments, the polynucleotide comprises a polynucleotide encoding a polypeptide comprising an amino acid sequence of SEQ ID NO:26. In some embodiments, the polynucleotide comprises a polynucleotide encoding a polypeptide comprising an amino acid sequence of SEQ ID NO:27. In some embodiments, the polynucleotide comprises a polynucleotide encoding a polypeptide comprising an amino acid sequence of SEQ ID NO:28. In some embodiments, the polynucleotide comprises a polynucleotide encoding a polypeptide comprising an amino acid sequence of SEQ ID NO:29. In some embodiments, the polynucleotide comprises a polynucleotide encoding a polypeptide comprising an amino acid sequence of SEQ ID NO:30. In some embodiments, the polynucleotide comprises a polynucleotide encoding a polypeptide comprising an amino acid sequence of SEQ ID NO:31. In some embodiments, the polynucleotide comprises a polynucleotide encoding a polypeptide comprising an amino acid sequence of SEQ ID NO:113. In some embodiments, the polynucleotide comprises a polynucleotide encoding a polypeptide comprising an amino acid sequence of SEQ ID NO:114. In some embodiments, the polynucleotide comprises a polynucleotide encoding a polypeptide comprising an amino acid sequence of SEQ ID NO: 119. In some embodiments, the polynucleotide comprises a polynucleotide encoding a polypeptide comprising an amino acid sequence of SEQ ID NO:229. In some embodiments, the polynucleotide comprises a polynucleotide (e.g., a nucleotide sequence) encoding a polypeptide comprising more than one amino acid sequence selected from the group consisting of: SEQ ID NOs:18-31, 91-108, and 110-112. In some embodiments, the polynucleotide comprises a polynucleotide encoding (i) a polypeptide comprising an amino acid sequence of SEQ ID NO:27 and (ii) a polypeptide comprising an amino acid sequence of SEQ ID NO:31. In some embodiments, the polynucleotide comprises a polynucleotide encoding (i) a polypeptide comprising an amino acid sequence of SEQ ID NO:29 and (ii) a polypeptide comprising an amino acid sequence of SEQ ID NO:31. In some embodiments, the polynucleotide comprises a polynucleotide encoding (i) a polypeptide comprising an amino acid sequence of SEQ ID NO:110 and (ii) a polypeptide comprising an amino acid sequence of SEQ ID NO:112. In some embodiments, the polynucleotide comprises a polynucleotide encoding (i) a polypeptide comprising an amino acid sequence of SEQ ID NO:111 and (ii) a polypeptide comprising an amino acid sequence of SEQ ID NO:112.

In some embodiments, a polynucleotide comprises a polynucleotide having a nucleotide sequence at least about 80% identical, at least about 85% identical, at least about 90% identical, at least about 95% identical, and in some embodiments, at least about 96%, 97%, 98%, or 99% identical to a polynucleotide encoding an amino acid sequence selected from the group consisting of: SEQ ID NOs:18-31, 91-108, 110-114, 119, and 229. Also provided is a polynucleotide that comprises a polynucleotide that hybridizes to a polynucleotide encoding an amino acid sequence selected from the group consisting of: SEQ ID NOs:18-31, 91-108, 110-114, 119, and 229. In some embodiments, the hybridization is under conditions of high stringency as is known to those skilled in the art.

In some embodiments, a polynucleotide comprises a polynucleotide having a nucleotide sequence that encodes an amino acid sequence selected from the group consisting of: SEQ ID NOs:26-31. In some embodiments, a polynucleotide comprises a polynucleotide having a nucleotide sequence that encodes an amino acid sequence of SEQ ID NO:26 or SEQ ID NO:27. In some embodiments, a polynucleotide comprises a polynucleotide having a nucleotide sequence that encodes an amino acid sequence of SEQ ID NO:28 or SEQ ID NO:29. In some embodiments, a polynucleotide comprises a polynucleotide having a nucleotide sequence that encodes an amino acid sequence of SEQ ID NO:30 or SEQ ID NO:31.

In certain embodiments, the polynucleotide encodes a heavy chain variable region comprising heavy chain CDRs 1, 2, and 3 of an amino acid sequence set forth in SEQ ID NOs:18, 20, 21, 22, 23, or 24. In certain embodiments, (a) heavy chain CDR1 comprises GYTFTDFYMD (SEQ ID NO:7), heavy chain CDR2 comprises YIYPHNGGTTYNQNFTG (SEQ ID NO:8), and heavy chain CDR3 comprises RGGFDFDY (SEQ ID NO:9); (b) heavy chain CDR1 comprises GYTFTDFYMD (SEQ ID NO:7), heavy chain CDR2 comprises YIYPHNGGTTYNQQFTG (SEQ ID NO:13), and heavy chain CDR3 comprises RGGFDFDY (SEQ ID NO:9); (c) heavy chain CDR1 comprises GYTFTDFYMD (SEQ ID NO:7), heavy chain CDR2 comprises YIYPHNAGTTYNQQFTG (SEQ ID NO:14), and heavy chain CDR3 comprises RGGFDFDY (SEQ ID NO:9); (d) heavy chain CDR1 comprises GYTFTDFYMD (SEQ ID NO:7), heavy chain CDR2 comprises YIYPHNTGTTYNQQFTG (SEQ ID NO:15), and heavy chain CDR3 comprises RGGFDFDY (SEQ ID NO:9); (e) heavy chain CDR1 comprises GYTFTDFYMD (SEQ ID NO:7), heavy chain CDR2 comprises YIYPHEGGTTYNQQFTG (SEQ ID NO:16), heavy chain CDR3 comprises RGGFDFDY (SEQ ID NO:9); or (f) heavy chain CDR1 comprises GYTFTDFYMD (SEQ ID NO:7), heavy chain CDR2 comprises YIYPHQGGTTYNQQFTG (SEQ ID NO:17), and heavy chain CDR3 comprises RGGFDFDY (SEQ ID NO:9). In certain embodiments, the polynucleotide encodes a light chain variable region comprising light chain CDRs 1, 2, and 3 of an amino acid sequence set forth in SEQ ID NO:19 or 25. In certain embodiments, light chain CDR1 comprises KASENVDTYVS (SEQ ID NO:10), light chain CDR2 comprises GASNRYT (SEQ ID NO:11), and light chain CDR3 comprises GQSHSYPLT (SEQ ID NO:12).

In certain embodiments, the polynucleotide encodes a heavy chain variable region comprising heavy chain CDRs 1, 2, and 3 of an amino acid sequence set forth in SEQ ID NO:91. In certain embodiments, heavy chain CDR1 comprises GYSFTGYNMN (SEQ ID NO:38), heavy chain CDR2 comprises NINPYYGSTNYNQKFKG (SEQ ID NO:39), and heavy chain CDR3 comprises GYYGGNYPFAY (SEQ ID NO:40). In certain embodiments, the polynucleotide encodes a light chain variable region comprising light chain CDRs 1, 2, and 3 of an amino acid sequence set forth in SEQ ID NO:92. In certain embodiments, light chain CDR1 comprises RASENIYSYLA (SEQ ID NO:41), light chain CDR2 comprises NAKTLAE (SEQ ID NO:42), and light chain CDR3 comprises QHYYGTPYT (SEQ ID NO:43).

In certain embodiments, the polynucleotide encodes a heavy chain variable region comprising heavy CDRs 1, 2, and 3 of an amino acid sequence set forth in SEQ ID NO:93. In certain embodiments, heavy chain CDR1 comprises GYSFTGYNMN (SEQ ID NO:38), heavy chain CDR2 comprises NINPYYDSTSYNQKFKG (SEQ ID NO:44), and heavy chain CDR3 comprises ENYDFVGFAY (SEQ ID NO:45). In certain embodiments, the polynucleotide encodes a light chain variable region comprising light chain CDRs 1, 2, and 3 of an amino acid sequence set forth in SEQ ID NO:94. In certain embodiments, light chain CDR1 comprises RASSSVSYMH (SEQ ID NO:46), light chain CDR2 comprises VTSNLAS (SEQ ID NO:47), and light chain CDR3 comprises QQWSTNPLT (SEQ ID NO:48).

In certain embodiments, the polynucleotide encodes a heavy chain variable region comprising heavy chain CDRs 1, 2, and 3 of an amino acid sequence set forth in SEQ ID NO:95. In certain embodiments, heavy chain CDR1 comprises GYSFTGYNMH (SEQ ID NO:49), heavy chain CDR2 comprises NINPYYGTTNSNQKFED (SEQ ID NO:50), and heavy chain CDR3 comprises GIYYYGTGYPYFDF (SEQ ID NO:51). In certain embodiments, the polynucleotide encodes a light chain variable region comprising light chain CDRs 1, 2, and 3 of an amino acid sequence set forth in SEQ ID NO:96. In certain embodiments, light chain CDR1 comprises RASQDINNYLN (SEQ ID NO:52), light chain CDR2 comprises YTSRLHS (SEQ ID NO:53), and light chain CDR3 comprises QQGITLPWT (SEQ ID NO:54).

In certain embodiments, the polynucleotide encodes a heavy chain variable region comprising heavy chain CDRs 1, 2, and 3 of an amino acid sequence set forth in SEQ ID NO:97. In certain embodiments, heavy chain CDR1 comprises GYTFTDYWIN (SEQ ID NO:55), heavy chain CDR2 comprises NIYPGSTSANYNEKFKS (SEQ ID NO:56), and heavy chain CDR3 comprises YGYDSWFAY (SEQ ID NO:57). In certain embodiments, the polynucleotide encodes a light chain variable region comprising light chain CDRs 1, 2, and 3 of an amino acid sequence set forth in SEQ ID NO:98. In certain embodiments, light chain CDR1 comprises KSTKSLLNSDGFTYLD (SEQ ID NO:58), light chain CDR2 comprises LVSNRFS (SEQ ID NO:59), and light chain CDR3 comprises FQSNYLPLT (SEQ ID NO:60).

In certain embodiments, the polynucleotide encodes a heavy chain variable region comprising heavy chain CDRs 1, 2, and 3 of an amino acid sequence set forth in SEQ ID NO:99. In certain embodiments, heavy chain CDR1 comprises GYAFNSCWMN (SEQ ID NO:61), heavy chain CDR2 comprises RIYPGDGDTNYNGKFKG (SEQ ID NO:62), and heavy chain CDR3 comprises EGRNYGYEDY (SEQ ID NO:63). In certain embodiments, the polynucleotide encodes a light chain variable region comprising light chain CDRs 1, 2, and 3 of an amino acid sequence set forth in SEQ ID NO:100. In certain embodiments, light chain CDR1 comprises KASQSVDYDGDSYMN (SEQ ID NO:64), light chain CDR2 comprises AASDLES (SEQ ID NO:65), and light chain CDR3 comprises QQANEDPRT (SEQ ID NO:66).

In certain embodiments, the polynucleotide encodes a heavy chain variable region comprising heavy chain CDRs 1, 2, and 3 of an amino acid sequence set forth in SEQ ID NO:101. In certain embodiments, heavy chain CDR1 comprises GFTFSNYAMS (SEQ ID NO:67), heavy chain CDR2 comprises QTISSGGRYTYYPDSVKG (SEQ ID NO:68), and heavy chain CDR3 comprises RYYGNSYWYFDV (SEQ ID NO:69). In certain embodiments, the polynucleotide encodes a light chain variable region comprising light chain CDRs 1, 2, and 3 of an amino acid sequence set forth in SEQ ID NO:102. In certain embodiments, light chain CDR1 comprises KSSQSLLNSGNQKHYLT (SEQ ID NO:70), light chain CDR2 comprises GASTRGS (SEQ ID NO:71), and light chain CDR3 comprises QNDHSYPYT (SEQ ID NO:72).

In certain embodiments, the polynucleotide encodes a heavy chain variable region comprising heavy chain CDRs 1, 2, and 3 of an amino acid sequence set forth in SEQ ID NO:103. In certain embodiments, heavy chain CDR1 comprises GFTFSSYTMS (SEQ ID NO:73), heavy chain CDR2 comprises YISSGGGTTYYPDTVKG (SEQ ID NO:74), and heavy chain CDR3 comprises RYYRGSSLWYFDV (SEQ ID NO:75). In certain embodiments, the polynucleotide encodes a light chain variable region comprising light chain CDRs 1, 2, and 3 of an amino acid sequence set forth in SEQ ID NO:104. In certain embodiments, light chain CDR1 comprises KSSQSLFNSGSQKNFLT (SEQ ID NO:76), light chain CDR2 comprises WASTRES (SEQ ID NO:77), and light chain CDR3 comprises QNDYSYPLT (SEQ ID NO:78).

In certain embodiments, the polynucleotide encodes a heavy chain variable region comprising heavy chain CDRs 1, 2, and 3 of an amino acid sequence set forth in SEQ ID NO:105. In certain embodiments, heavy chain CDR1 comprises GYSITSGYSLH (SEQ ID NO:79), heavy chain CDR2 comprises YIHYSGSTNYNPSLKS (SEQ ID NO:80), and heavy chain CDR3 comprises AWDYLDY (SEQ ID NO:81). In certain embodiments, the polynucleotide encodes a light chain variable region comprising light chain CDRs 1, 2, and 3 of an amino acid sequence set forth in SEQ ID NO:106. In certain embodiments, light chain CDR1 comprises RASENIYSQLA (SEQ ID NO:82), light chain CDR2 comprises DAKTLAE (SEQ ID NO:83), and light chain CDR3 comprises HHHFGILYT (SEQ ID NO:84).

In certain embodiments, the polynucleotide encodes a heavy chain variable region comprising heavy chain CDRs 1, 2, and 3 of an amino acid sequence set forth in SEQ ID NO:107. In certain embodiments, heavy chain CDR1 comprises GYSITSGYYWN (SEQ ID NO:85), heavy chain CDR2 comprises YIRYDGSNNYNPSLKN (SEQ ID NO:86), and heavy chain CDR3 comprises HYGYDGGAFDF (SEQ ID NO:87). In certain embodiments, the polynucleotide encodes a light chain variable region comprising light chain CDRs 1, 2, and 3 of an amino acid sequence set forth in SEQ ID NO:108. In certain embodiments, light chain CDR1 comprises RTSENIYNYLV (SEQ ID NO:88), light chain CDR2 comprises NAKTLEE (SEQ ID NO:89), and light chain CDR3 comprises QHHYGTPFT (SEQ ID NO:90).

In certain embodiments, the polynucleotide encodes a dsscFv comprising a heavy chain variable region and a light chain variable region, wherein the heavy chain variable region comprises an amino acid sequence set forth in SEQ ID NO:110 or SEQ ID NO:111, and the light chain variable region comprises an amino acid sequence set forth in SEQ ID NO:112. In certain embodiments, the dsscFv comprises an amino acid sequence of SEQ ID NO:113 or SEQ ID NO:114.

In some embodiments, a polynucleotide comprises the coding sequence for a polypeptide (e.g., an antibody) fused in the same reading frame to a polynucleotide which aids in expression and secretion of a polypeptide from a host cell (e.g., a leader sequence which functions as a secretory sequence for controlling transport of a polypeptide). The polypeptide can have the leader sequence cleaved by the host cell to form a “mature” form of the polypeptide.

In some embodiments, a polynucleotide comprises the coding sequence for a polypeptide (e.g., an antibody) fused in the same reading frame to a marker or tag sequence. For example, in some embodiments, a marker sequence is a hexa-histidine tag (SEQ ID NO:231) (HIS-tag) that allows for efficient purification of the polypeptide fused to the marker. In some embodiments, a marker sequence is a hemagglutinin (HA) tag derived from the influenza hemagglutinin protein when a mammalian host (e.g., COS-7 cells) is used. In some embodiments, the marker sequence is a FLAG™ tag. In some embodiments, a marker may be used in conjunction with other markers or tags.

The present disclosure also provides variants of the polynucleotides described herein, wherein the variant encodes, for example, fragments, analogs, and/or derivatives of a polypeptide. In some embodiments, the present disclosure provides a polynucleotide comprising a polynucleotide having a nucleotide sequence at least about 80% identical, at least about 85% identical, at least about 90% identical, at least about 95% identical, and in some embodiments, at least about 96%, 97%, 98% or 99% identical to a polynucleotide sequence encoding a polypeptide described herein.

As used herein, the phrase “a polynucleotide having a nucleotide sequence at least about 95% identical to a polynucleotide sequence” is intended to mean that the nucleotide sequence of the polynucleotide is identical to a reference sequence except that the polynucleotide sequence can include up to five point mutations per each 100 nucleotides of the reference nucleotide sequence. In other words, to obtain a polynucleotide having a nucleotide sequence at least 95% identical to a reference nucleotide sequence, up to 5% of the nucleotides in the reference sequence can be deleted or substituted with another nucleotide, or a number of nucleotides up to 5% of the total nucleotides in the reference sequence can be inserted into the reference sequence. These mutations of the reference sequence can occur at the 5′ or 3′ terminal positions of the reference nucleotide sequence or anywhere between those terminal positions, interspersed either individually among nucleotides in the reference sequence or in one or more contiguous groups within the reference sequence.

The polynucleotide variants can contain alterations in the coding regions, non-coding regions, or both. In some embodiments, a polynucleotide variant contains alterations which produce silent substitutions, additions, or deletions, but does not alter the properties or activities of the encoded polypeptide. In some embodiments, a polynucleotide variant comprises silent substitutions that results in no change to the amino acid sequence of the polypeptide (due to the degeneracy of the genetic code). In some embodiments, a polynucleotide variant comprises one or more mutated codons comprising one or more (e.g., 1, 2, or 3) substitutions to the codon that change the amino acid encoded by that codon. Methods for introducing one or more substitutions into a codon are known in the art, such as, e.g., PCR mutagenesis and site-directed mutagenesis. Polynucleotide variants can be produced for a variety of reasons, for example, to optimize codon expression for a particular host (e.g., change codons in the human mRNA to those preferred by a bacterial host such as E. coli). In some embodiments, a polynucleotide variant comprises at least one silent mutation in a non-coding or a coding region of the sequence.

In some embodiments, a polynucleotide variant is produced to modulate or alter expression (or expression levels) of the encoded polypeptide. In some embodiments, a polynucleotide variant is produced to increase expression of the encoded polypeptide. In some embodiments, a polynucleotide variant is produced to decrease expression of the encoded polypeptide. In some embodiments, a polynucleotide variant has increased expression of the encoded polypeptide as compared to a parental polynucleotide sequence. In some embodiments, a polynucleotide variant has decreased expression of the encoded polypeptide as compared to a parental polynucleotide sequence.

In some embodiments, a polynucleotide is isolated. In some embodiments, a polynucleotide is substantially pure.

Vectors and cells comprising each and every one of the polynucleotides described herein are also provided. In some embodiments, an expression vector comprises a polynucleotide molecule encoding a C3-binding agent described herein. In some embodiments, an expression vector comprises a polynucleotide molecule encoding a polypeptide that is part of a C3-binding agent described herein. In some embodiments, a host cell comprises an expression vector comprising a polynucleotide molecule encoding a C3-binding agent described herein. In some embodiments, a host cell comprises an expression vector comprising a polynucleotide molecule encoding a polypeptide that is part of a C3-binding agent described herein. In some embodiments, a host cell comprises a polynucleotide molecule encoding a C3-binding agent described herein.

IV. Methods of Making Binding Agents

The disclosure provides a method for making the C3-binding agents (e.g., antibodies) described herein. In certain embodiments in which the C3-binding agent is an antibody, the method involves providing a cell comprising a heavy chain and/or light chain of the C3-binding agent, incubating the cell under conditions that permit the expression of the antibody and isolating the antibody. In certain embodiments, the cell comprises one or more vectors (e.g., one or more vectors described herein) encoding the heavy chain and the light chain. For example, in certain embodiments, the cell comprises a first vector encoding the heavy chain and a second vector encoding the light chain. In other embodiments, the cell comprises a vector encoding the heavy chain and the light chain. In certain embodiments, the cell comprises one or more polynucleotides (e.g., one or more polynucleotides described herein) encoding the heavy chain and the light chain. For example, in certain embodiments, the cell comprises a first polynucleotide encoding the heavy chain and a second polynucleotide encoding the light chain.

In other embodiments, the cell comprises a polynucleotide encoding the heavy chain and the light chain. In some embodiments, the method comprises purifying the antibody. In certain embodiments, the cell is a CHO cell. In other embodiments, the cell is a 293 cell. In certain embodiments, the cell is a bacterial cell (e.g., E. coli).

In certain embodiments in which the C3-binding agent is an scFv (e.g., a dsscFv), the method involves providing a cell comprising the scFv (e.g., a dsscFv) of the C3-binding agent, incubating the cell under conditions that permit the expression of the scFv and isolating the scFv. In certain embodiments, the cell comprises a vector (e.g., a vector described herein) encoding the scFv. In certain embodiments, the cell comprises a polynucleotide (e.g., a polynucleotide described herein) encoding the scFv. In some embodiments, the method comprises purifying the antibody. In certain embodiments, the cell is a bacterial cell (e.g., E. coli). In certain embodiments, the cell is a yeast cell (e.g., Pichia pastoris). In certain embodiments, the cell is a CHO cell. In other embodiments, the cell is a 293 cell.

V. Methods of Use and Pharmaceutical Compositions

The C3-binding agents (e.g., antibodies) of the disclosure are useful in a variety of applications including, but not limited to, therapeutic treatment methods, such as treatment of diseases or disorders associated with complement activation. In some embodiments, a C3-binding agent described herein is useful in methods for inhibiting complement activation. In some embodiments, a C3-binding agent described herein is useful in methods for inhibiting C3 activity. In some embodiments, a C3-binding agent described herein is useful in methods for treating an eye disorder. In some embodiments, a C3-binding agent described herein is useful in methods for inhibiting or suppressing drusen formation in an eye. In some embodiments, a C3-binding agent described herein is useful in methods for treating macular degeneration. In some embodiments, a C3-binding agent described herein is useful in methods for treating a disorder associated with macular degeneration. In some embodiments, a C3-binding agent described herein is useful in methods for treating age-related macular degeneration (AMD). In some embodiments, a C3-binding agent described herein is useful in methods for treating dry AMD. In some embodiments, a C3-binding agent described herein is useful in methods for treating early AMD. In some embodiments, a C3-binding agent described herein is useful in methods for treating intermediate AMD. In some embodiments, a C3-binding agent described herein is useful in methods for treating advanced dry AMD/geographic atrophy. The terms “advanced dry AMD” and “geographic atrophy” are used interchangeably herein.

In some embodiments, a method of inhibiting complement activation in an eye of a subject (e.g., a human) comprises administering to the subject a therapeutically effective amount of a C3-binding agent described herein. In some embodiments, a method of inhibiting complement activation in an eye of a subject (e.g., a human) comprises administering to the subject a therapeutically effective amount of an anti-C3 antibody described herein. In some embodiments, a method of inhibiting C3 activity in an eye of a subject (e.g., a human) comprises administering to the subject a therapeutically effective amount of a C3-binding agent described herein. In some embodiments, a method of inhibiting C3 activity in an eye of a subject (e.g., a human) comprises administering to the subject a therapeutically effective amount of an anti-C3 antibody described herein. In some embodiments of the methods described herein the C3-binding agent is administered to an eye of the subject. In some embodiments of the methods described herein the anti-C3 antibody is administered to an eye of the subject.

In some embodiments, a method of treating an eye disorder in a subject (e.g., a human) comprises administering to the subject a therapeutically effective amount of a C3-binding agent described herein. In some embodiments, a method of treating an eye disorder in a subject (e.g., a human) comprises administering to the subject a therapeutically effective amount of an anti-C3 antibody described herein. In some embodiments, the eye disorder is selected from the group consisting of: macular degeneration (maculopathy), age-related macular degeneration (AMD), diabetic retinopathy, retinopathy of prematurity, macular dystrophy, retinal dystrophy, uveitis, keratitis, scleritis, retinitis pigmentosa, choroidal neovascularization, retinal neovascularization, and ocular inflammation. In some embodiments, the eye disorder is macular degeneration. In some embodiments, the eye disorder is AMD. In some embodiments, the eye disorder is wet AMD. In some embodiments, the eye disorder is dry AMD. In some embodiments, the eye disorder is early AMD. In some embodiments, the eye disorder is intermediate AMD. In some embodiments, the eye disorder is geographic atrophy.

In the early stages of AMD, the disease is characterized by the presence of drusen, which can manifest with or without retinal pigment epithelium (RPE) irregularities. In the early stages when drusen are small and/or few, vision is generally not affected. As drusen enlarge and multiply in number, patients report that central vision is less sharp. Geographic atrophy (GA) is the advanced form of dry AMD. GA is characterized by the degeneration of RPE, wherein the degeneration of the RPE leads to the death of photoreceptor cells (the rods and cones). Thus, a patient has a spot or area (a “continent”) of atrophy surrounded by a “sea” of healthy or healthier-looking retina. Doctors can measure the area of atrophy (often referred to as “GA lesion area”) and estimate the loss of visual function. Changes in the GA lesion area can be used to follow progression of the disease over time.

In some embodiments, a method of treating AMD in a subject (e.g., a human) comprises administering to the subject a therapeutically effective amount of a C3-binding agent described herein. In some embodiments, a method of treating AMD in a subject (e.g., a human) comprises administering to the subject a therapeutically effective amount of an antibody that specifically binds C3 (e.g., human C3) described herein. In some embodiments, the AMD is dry AMD. In some embodiments, the AMD is early AMD. In some embodiments, the AMD is intermediate AMD. In some embodiments, the AMD is GA. In some embodiments, a method of treating geographic atrophy in a subject (e.g., a human) comprises administering to the subject a therapeutically effective amount of a C3-binding agent described herein. In some embodiments, a method of treating geographic atrophy in a subject (e.g., a human) comprises administering to the subject a therapeutically effective amount of an antibody that specifically binds C3 described herein.

In some embodiments, a method of inhibiting or suppressing drusen formation in an eye of a subject (e.g., a human) comprises administering to the subject a therapeutically effective amount of a C3-binding agent described herein. In some embodiments, a method of inhibiting or suppressing drusen formation in an eye of a subject (e.g., a human) comprises administering to the subject a therapeutically effective amount of an anti-C3 antibody described herein.

In some embodiments, a method of inhibiting or suppressing retinal pigment epithelium atrophy in an eye of a subject (e.g., a human) comprises administering to the subject a therapeutically effective amount of C3-binding agent described herein. In some embodiments, a method of inhibiting or suppressing retinal pigment epithelium atrophy in an eye of a subject (e.g., a human) comprises administering to the subject a therapeutically effective amount of an anti-C3 antibody described herein.

In some embodiments, a method of treating a subject (e.g., a human) at risk of developing AMD comprises administering to the subject a therapeutically effective amount of a C3-binding agent described herein. In some embodiments, a method of treating a subject (e.g. a human) at risk of developing AMD comprises administering to the subject a therapeutically effective amount of an anti-C3 antibody described herein. In some embodiments, a method of treating a subject (e.g., a human) at risk of developing geographic atrophy comprises administering to the subject a therapeutically effective amount of a C3-binding agent described herein. In some embodiments, a method of treating a subject (e.g., a human) at risk of developing geographic atrophy comprises administering to the subject a therapeutically effective amount of an anti-C3 antibody described herein.

In some embodiments, a method of slowing down or reducing the progression of AMD in a subject (e.g., a human) comprises administering to the subject a therapeutically effective amount of a C3-binding agent described herein. In some embodiments, a method of slowing down or reducing the progression of AMD in a subject (e.g., a human) comprises administering to the subject a therapeutically effective amount of an anti-C3 antibody described herein. In some embodiments, the method slows down or reduces progression of early AMD to intermediate AMD. In some embodiments, the method slows down or reduces progression of intermediate AMD to geographic atrophy. In some embodiments, a method of slowing down or reducing the progression of geographic atrophy in a subject (e.g., a human) comprises administering to the subject a C3-binding agent described herein. In some embodiments, a method of slowing down or reducing the progression of geographic atrophy in a subject (e.g., a human) comprises administering to the subject a therapeutically effective amount of an anti-C3 antibody described herein.

In some embodiments of the methods described herein, a subject (e.g., a human) has AMD or GA. In some embodiments of the methods described herein, a subject (e.g., a human) has been diagnosed with AMD or GA. The criteria for diagnosis of AMD and GA differ across grading systems and may depend upon the imaging modalities that are used. In some embodiments, the criteria for AMD comprises: (1) No AMD—no or a few small (<63 pm in diameter) drusen; (2) Early AMD—intermediate-sized (63-124 pm in diameter) drusen; (3) Intermediate AMD—intermediate-sized drusen and pigmentary changes or at least 1 large (>125 pm) drusen; (4) Late AMD (dry)—geographic atrophy or Late AMD (wet)—CNV with signs including subretinal hemorrhage, serous retinal or retinal pigment epithelium detachments, lipid exudates, or fibrovascular scarring. In some embodiments, the criteria for GA comprises an area of pallor in the fundus with visibility of the underlying choroidal blood vessels and sharply defined borders, occupying (1) a diameter >175 pm; (2) a diameter >250 pm; or (3) a diameter of at least 433 pm. Currently, there is no consensus on the minimum diameter for the diagnosis of GA.

There are a number of imaging modalities used by medical practitioners skilled in the art, including but not limited to, color fundus photography (CFP), fundus autofluorescence (FAF), optical coherence tomography (OCT), fluorescein angiography (FA), and indocyanine green angiography (ICGA). Imaging modalities allow for the direct measurement and quantification of GA lesion area.

Thus, in some embodiments, a method of treating geographic atrophy in a subject (e.g., a human) comprises administering to the subject a therapeutically effective amount of an antibody that specifically binds C3 described herein, wherein the treatment reduces growth of the GA lesion area. In some embodiments, the GA lesion area is measured by color fundus photography, fluorescein angiography, and/or optical coherence tomography. In some embodiments, the GA lesion is measured prior to treatment with an anti-C3 antibody and measured again after treatment. In some embodiments, growth of the GA lesion area is reduced by about 20%, about 30%, about 40%, about 50%, about 60%, about 70%, or about 80% or better. In some embodiments, growth of the GA lesion area is reduced by at least 25%. In some embodiments, growth of the GA lesion is reduced by at least 40%. In some embodiments, growth of the GA lesion is reduced by at least 50%. In some embodiments, the GA lesion area is measured about 6 months after treatment, about 1 year after treatment, about 18 months after treatment, and/or about 2 years after treatment. In some embodiments, the GA lesion area is measured every time the C3-binding agent is administered. In some embodiments, the GA lesion area is measured at time points chosen by the medical practitioner.

In some embodiments of the methods described herein, the C3-binding agent (e.g., an anti-C3 antibody) comprises a heavy chain CDR1, CDR2, and CDR3 and a light chain CDR1, CDR2, and CDR3 of antibody 38G10. In some embodiments of the methods described herein, the C3-binding agent (e.g., an anti-C3 antibody) comprises a heavy chain CDR1, CDR2, and CDR3 and a light chain CDR1, CDR2, and CDR3 of antibody Hz38G10. In some embodiments of the methods described herein, the C3-binding agent (e.g., an anti-C3 antibody) comprises a heavy chain CDR1, CDR2, and CDR3 and a light chain CDR1, CDR2, and CDR3 of antibody Hz38G10(G56A). In some embodiments of the methods described herein, the C3-binding agent (e.g., an anti-C3 antibody) comprises a heavy chain CDR1, CDR2, and CDR3 and a light chain CDR1, CDR2, and CDR3 of antibody Hz38G10(G56T). In some embodiments of the methods described herein, the C3-binding agent (e.g. anti-C3 antibody) comprises a heavy chain CDR1, CDR2, and CDR3 and a light chain CDR1, CDR2, and CDR3 of antibody Hz38G10(N55E). In some embodiments of the methods described herein, the C3-binding agent (e.g. anti-C3 antibody) comprises a heavy chain CDR1, CDR2, and CDR3 and a light chain CDR1, CDR2, and CDR3 of antibody Hz38G10(N55Q). In some embodiments of the methods described herein, the C3-binding agent (e.g. anti-C3 antibody) comprises a heavy chain CDR1, CDR2, and CDR3 and a light chain CDR1, CDR2, and CDR3 of antibody 3D8. In some embodiments of the methods described herein, the C3-binding agent (e.g. anti-C3 antibody) comprises a heavy chain CDR1, CDR2, and CDR3 and a light chain CDR1, CDR2, and CDR3 of antibody 3G8. In some embodiments of the methods described herein, the C3-binding agent (e.g. anti-C3 antibody) comprises a heavy chain CDR1, CDR2, and CDR3 and a light chain CDR1, CDR2, and CDR3 of antibody 15C12. In some embodiments of the methods described herein, the C3-binding agent (e.g. anti-C3 antibody) comprises a heavy chain CDR1, CDR2, and CDR3 and a light chain CDR1, CDR2, and CDR3 of antibody 27A8. In some embodiments of the methods described herein, the C3-binding agent (e.g. anti-C3 antibody) comprises a heavy chain CDR1, CDR2, and CDR3 and a light chain CDR1, CDR2, and CDR3 of antibody 28C3. In some embodiments of the methods described herein, the C3-binding agent (e.g. anti-C3 antibody) comprises a heavy chain CDR1, CDR2, and CDR3 and a light chain CDR1, CDR2, and CDR3 of antibody 38F5. In some embodiments of the methods described herein, the C3-binding agent (e.g. anti-C3 antibody) comprises a heavy chain CDR1, CDR2, and CDR3 and a light chain CDR1, CDR2, and CDR3 of antibody 62B11. In some embodiments of the methods described herein, the C3-binding agent (e.g. anti-C3 antibody) comprises a heavy chain CDR1, CDR2, and CDR3 and a light chain CDR1, CDR2, and CDR3 of antibody 62F2. In some embodiments of the methods described herein, the C3-binding agent (e.g. anti-C3 antibody) comprises a heavy chain CDR1, CDR2, and CDR3 and a light chain CDR1, CDR2, and CDR3 of antibody 63A3.

In some embodiments of the methods described herein, the C3-binding agent is a humanized anti-C3 antibody having the above specified CDRs.

In some embodiments of the methods described herein, the anti-C3 antibody comprises a heavy chain CDR1 comprising GYTFTDFYMD (SEQ ID NO:7); a heavy chain CDR2 comprising YIYPHNGGTTYNQQFTG (SEQ ID NO:13), YIYPHNAGTTYNQQFTG (SEQ ID NO:14), YIYPHNTGTTYNQQFTG (SEQ ID NO:15), YIYPHEGGTTYNQQFTG (SEQ ID NO:16), or YIYPHQGGTTYNQQFTG (SEQ ID NO:17); and a heavy chain CDR3 comprising RGGFDFDY (SEQ ID NO:9), and a light chain CDR1 comprising KASENVDTYVS (SEQ ID NO:10); a light chain CDR2 comprising GASNRYT (SEQ ID NO:11); and a light chain CDR3 comprising GQSHSYPLT (SEQ ID NO:12). In some embodiments of the methods described herein, the anti-C3 antibody comprises a heavy chain CDR1 comprising GYTFTDFYMD (SEQ ID NO:7); a heavy chain CDR2 comprising YIYPHNGGTTYNQQFTG (SEQ ID NO:13); a heavy chain CDR3 comprising RGGFDFDY (SEQ ID NO:9), a light chain CDR1 comprising KASENVDTYVS (SEQ ID NO:10); a light chain CDR2 comprising GASNRYT (SEQ ID NO:11); and a light chain CDR3 comprising GQSHSYPLT (SEQ ID NO:12). In some embodiments of the methods described herein, the anti-C3 antibody comprises a heavy chain CDR1 comprising GYTFTDFYMD (SEQ ID NO:7); a heavy chain CDR2 comprising YIYPHNAGTTYNQQFTG (SEQ ID NO:14); a heavy chain CDR3 comprising RGGFDFDY (SEQ ID NO:9), a light chain CDR1 comprising KASENVDTYVS (SEQ ID NO:10); a light chain CDR2 comprising GASNRYT (SEQ ID NO:11); and a light chain CDR3 comprising GQSHSYPLT (SEQ ID NO:12). In some embodiments of the methods described herein, the anti-C3 antibody comprises a heavy chain CDR1 comprising GYTFTDFYMD (SEQ ID NO:7); a heavy chain CDR2 comprising YIYPHNTGTTYNQQFTG (SEQ ID NO:15); a heavy chain CDR3 comprising RGGFDFDY (SEQ ID NO:9), a light chain CDR1 comprising KASENVDTYVS (SEQ ID NO:10); a light chain CDR2 comprising GASNRYT (SEQ ID NO:11); and a light chain CDR3 comprising GQSHSYPLT (SEQ ID NO:12).

In some embodiments of the methods described herein, the anti-C3 antibody comprises: (a) a heavy chain variable region of SEQ ID NO:20, SEQ ID NO:21, SEQ ID NO:22, SEQ ID NO:23, or SEQ ID NO:24; and (b) a light chain variable region of SEQ ID NO:25. In some embodiments of the methods described herein, the anti-C3 antibody comprises: (a) a heavy chain variable region of SEQ ID NO:20 and (b) a light chain variable region of SEQ ID NO:25. In some embodiments of the methods described herein, the anti-C3 antibody comprises: (a) a heavy chain variable region of SEQ ID NO:21 and (b) a light chain variable region of SEQ ID NO:25. In some embodiments of the methods described herein, the anti-C3 antibody comprises: (a) a heavy chain variable region of SEQ ID NO:22 and (b) a light chain variable region of SEQ ID NO:25. In some embodiments of the methods described herein, the anti-C3 antibody comprises: (a) a heavy chain variable region of SEQ ID NO:23 and (b) a light chain variable region of SEQ ID NO:25. In some embodiments of the methods described herein, the anti-C3 antibody comprises: (a) a heavy chain variable region of SEQ ID NO:24 and (b) a light chain variable region of SEQ ID NO:25. In some embodiments of the methods described herein, the anti-C3 antibody is Hz38G10. In some embodiments of the methods described herein, the anti-C3 antibody is Hz38G10(G56A). In some embodiments of the methods described herein, the anti-C3 antibody is Hz38G10(G56T). In some embodiments of the methods described herein, the anti-C3 antibody is Hz38G10(N55E). In some embodiments of the methods described herein, the anti-C3 antibody is Hz38G10(N55Q).

In some embodiments of the methods described herein, the anti-C3 antibody comprises a polypeptide of SEQ ID NO:27. In some embodiments of the methods described herein, the anti-C3 antibody comprises a polypeptide of SEQ ID NO:29. In some embodiments of the methods described herein, the anti-C3 antibody comprises a polypeptide of SEQ ID NO:31. In some embodiments of the methods described herein, the anti-C3 antibody comprises a polypeptide of SEQ ID NO:27 and a polypeptide of SEQ ID NO:31. In some embodiments of the methods described herein, the anti-C3 antibody comprises a polypeptide of SEQ ID NO:29 and a polypeptide of SEQ ID NO:31.

In some embodiments of the methods described herein, the anti-C3 antibody comprises a polypeptide of SEQ ID NO:110 and a polypeptide of SEQ ID NO:112. In some embodiments of the methods described herein, the anti-C3 antibody comprises a polypeptide of SEQ ID NO:111 and a polypeptide of SEQ ID NO:112. In some embodiments of the methods described herein, the anti-C3 antibody comprises a polypeptide of SEQ ID NO:113. In some embodiments of the methods described herein, the anti-C3 antibody comprises a polypeptide of SEQ ID NO:114. In some embodiments of the methods described herein, the anti-C3 antibody comprises a polypeptide of SEQ ID NO:119. In some embodiments of the methods described herein, the anti-C3 antibody comprises a polypeptide of SEQ ID NO:229.

In certain embodiments of the methods described herein, the C3-binding agent comprises a heavy chain variable region and a light chain variable region, wherein the heavy chain variable region comprises heavy chain CDRs 1, 2, and 3 of an amino acid sequence set forth in SEQ ID NO:18, and the light chain variable region comprises light chain CDRs 1, 2, and 3 of an amino acid sequence set forth in SEQ ID NO:19. In certain embodiments, heavy chain CDR1 comprises GYTFTDFYMD (SEQ ID NO:7), heavy chain CDR2 comprises YIYPHNGGTTYNQNFTG (SEQ ID NO:8), heavy chain CDR3 comprises RGGFDFDY (SEQ ID NO:9), light chain CDR1 comprises KASENVDTYVS (SEQ ID NO:10), light chain CDR2 comprises GASNRYT (SEQ ID NO:11), and light chain CDR3 comprises GQSHSYPLT (SEQ ID NO:12).

In certain embodiments of the methods described herein, the C3-binding agent comprises a heavy chain variable region and a light chain variable region, wherein the heavy chain variable region comprises heavy chain CDRs 1, 2, and 3 of an amino acid sequence set forth in SEQ ID NO:20, and the light chain variable region comprises light chain CDRs 1, 2, and 3 of an amino acid sequence set forth in SEQ ID NO:25. In certain embodiments, chain CDR1 comprises GYTFTDFYMD (SEQ ID NO:7), heavy chain CDR2 comprises YIYPHNGGTTYNQQFTG (SEQ ID NO:13), heavy chain CDR3 comprises RGGFDFDY (SEQ ID NO:9), light chain CDR1 comprises KASENVDTYVS (SEQ ID NO:10), light chain CDR2 comprises GASNRYT (SEQ ID NO:11), and light chain CDR3 comprises GQSHSYPLT (SEQ ID NO:12).

In certain embodiments of the methods described herein, the C3-binding agent comprises a heavy chain variable region and a light chain variable region, wherein the heavy chain variable region comprises heavy chain CDRs 1, 2, and 3 of an amino acid sequence set forth in SEQ ID NO:21, and the light chain variable region comprises light chain CDRs 1, 2, and 3 of an amino acid sequence set forth in SEQ ID NO:25. In certain embodiments, heavy chain CDR1 comprises GYTFTDFYMD (SEQ ID NO:7), heavy chain CDR2 comprises YIYPHNAGTTYNQQFTG (SEQ ID NO:14), heavy chain CDR3 comprises RGGFDFDY (SEQ ID NO:9), light chain CDR1 comprises KASENVDTYVS (SEQ ID NO:10), light chain CDR2 comprises GASNRYT (SEQ ID NO:11), and light chain CDR3 comprises GQSHSYPLT (SEQ ID NO:12).

In certain embodiments of the methods described herein, the C3-binding agent comprises a heavy chain variable region and a light chain variable region, wherein the heavy chain variable region comprises heavy chain CDRs 1, 2, and 3 of an amino acid sequence set forth in SEQ ID NO:22, and the light chain variable region comprises light chain CDRs 1, 2, and 3 of an amino acid sequence set forth in SEQ ID NO:25. In certain embodiments, heavy chain CDR1 comprises GYTFTDFYMD (SEQ ID NO:7), heavy chain CDR2 comprises YIYPHNTGTTYNQQFTG (SEQ ID NO:15), heavy chain CDR3 comprises RGGFDFDY (SEQ ID NO:9), light chain CDR1 comprises KASENVDTYVS (SEQ ID NO:10), light chain CDR2 comprises GASNRYT (SEQ ID NO:11), and light chain CDR3 comprises GQSHSYPLT (SEQ ID NO:12).

In certain embodiments of the methods described herein, the C3-binding agent comprises a heavy chain variable region and a light chain variable region, wherein the heavy chain variable region comprises heavy chain CDRs 1, 2, and 3 of an amino acid sequence set forth in SEQ ID NO:23, and the light chain variable region comprises light chain CDRs 1, 2, and 3 of an amino acid sequence set forth in SEQ ID NO:25. In certain embodiments, heavy chain CDR1 comprises GYTFTDFYMD (SEQ ID NO:7), heavy chain CDR2 comprises YIYPHEGGTTYNQQFTG (SEQ ID NO:16), heavy chain CDR3 comprises RGGFDFDY (SEQ ID NO:9), light chain CDR1 comprises KASENVDTYVS (SEQ ID NO:10), light chain CDR2 comprises GASNRYT (SEQ ID NO:11), and light chain CDR3 comprises GQSHSYPLT (SEQ ID NO:12).

In certain embodiments of the methods described herein, the C3-binding agent comprises a heavy chain variable region and a light chain variable region, wherein the heavy chain variable region comprises heavy chain CDRs 1, 2, and 3 of an amino acid sequence set forth in SEQ ID NO:24, and the light chain variable region comprises light chain CDRs 1, 2, and 3 of an amino acid sequence set forth in SEQ ID NO:25. In certain embodiments, heavy chain CDR1 comprises GYTFTDFYMD (SEQ ID NO:7), heavy chain CDR2 comprises YIYPHQGGTTYNQQFTG (SEQ ID NO:17), heavy chain CDR3 comprises RGGFDFDY (SEQ ID NO:9), light chain CDR1 comprises KASENVDTYVS (SEQ ID NO:10), light chain CDR2 comprises GASNRYT (SEQ ID NO:11), and light chain CDR3 comprises GQSHSYPLT (SEQ ID NO:12).

In certain embodiments of the methods described herein, the C3-binding agent comprises which comprises a heavy chain variable region and a light chain variable region, wherein the heavy chain variable region comprises heavy chain CDRs 1, 2, and 3 of an amino acid sequence set forth in SEQ ID NO:91, and the light chain variable region comprises light chain CDRs 1, 2, and 3 of an amino acid sequence set forth in SEQ ID NO:92. In certain embodiments, heavy chain CDR1 comprises GYSFTGYNMN (SEQ ID NO:38), heavy chain CDR2 comprises NINPYYGSTNYNQKFKG (SEQ ID NO:39), heavy chain CDR3 comprises GYYGGNYPFAY (SEQ ID NO:40), light chain CDR1 comprises RASENIYSYLA (SEQ ID NO:41), light chain CDR2 comprises NAKTLAE (SEQ ID NO: 42), and light chain CDR3 comprises QHYYGTPYT (SEQ ID NO:43).

In certain embodiments of the methods described herein, the C3-binding agent comprises a heavy chain variable region and a light chain variable region, wherein the heavy chain variable region comprises heavy chain CDRs 1, 2, and 3 of an amino acid sequence set forth in SEQ ID NO:93, and the light chain variable region comprises light chain CDRs 1, 2, and 3 of an amino acid sequence set forth in SEQ ID NO:94. In certain embodiments, heavy chain CDR1 comprises GYSFTGYNMN (SEQ ID NO:38), heavy chain CDR2 comprises NINPYYDSTSYNQKFKG (SEQ ID NO:44), heavy chain CDR3 comprises ENYDFVGFAY (SEQ ID NO:45), light chain CDR1 comprises RASSSVSYMH (SEQ ID NO:46), light chain CDR2 comprises VTSNLAS (SEQ ID NO:47), and light chain CDR3 comprises QQWSTNPLT (SEQ ID NO:48).

In certain embodiments of the methods described herein, the C3-binding agent comprises a heavy chain variable region and a light chain variable region, wherein the heavy chain variable region comprises heavy chain CDRs 1, 2, and 3 of an amino acid sequence set forth in SEQ ID NO:95, and the light chain variable region comprises light chain CDRs 1, 2, and 3 of an amino acid sequence set forth in SEQ ID NO:96. In certain embodiments, heavy chain CDR1 comprises GYSFTGYNMH (SEQ ID NO:49), heavy chain CDR2 comprises NINPYYGTTNSNQKFED (SEQ ID NO:50), heavy chain CDR3 comprises GIYYYGTGYPYFDF (SEQ ID NO:51), light chain CDR1 comprises RASQDINNYLN (SEQ ID NO:52), light chain CDR2 comprises YTSRLHS (SEQ ID NO:53), and light chain CDR3 comprises QQGITLPWT (SEQ ID NO:54).

In certain embodiments of the methods described herein, the C3-binding agent comprises a heavy chain variable region and a light chain variable region, wherein the heavy chain variable region comprises heavy chain CDRs 1, 2, and 3 of an amino acid sequence set forth in SEQ ID NO:97, and the light chain variable region comprises light chain CDRs 1, 2, and 3 of an amino acid sequence set forth in SEQ ID NO:98. In certain embodiments, heavy chain CDR1 comprises GYTFTDYWIN (SEQ ID NO:55), heavy chain CDR2 comprises NIYPGSTSANYNEKFKS (SEQ ID NO:56), heavy chain CDR3 comprises YGYDSWFAY (SEQ ID NO:57), light chain CDR1 comprises KSTKSLLNSDGFTYLD (SEQ ID NO:58), light chain CDR2 comprises LVSNRFS (SEQ ID NO:59), and light chain CDR3 comprises FQSNYLPLT (SEQ ID NO:60).

In certain embodiments of the methods described herein, the C3-binding agent comprises a heavy chain variable region and a light chain variable region, wherein the heavy chain variable region comprises heavy chain CDRs 1, 2, and 3 of an amino acid sequence set forth in SEQ ID NO:99, and the light chain variable region comprises light chain CDRs 1, 2, and 3 of an amino acid sequence set forth in SEQ ID NO:100. In certain embodiments, heavy chain CDR1 comprises GYAFNSCWMN (SEQ ID NO:61), heavy chain CDR2 comprises RIYPGDGDTNYNGKFKG (SEQ ID NO:62), heavy chain CDR3 comprises EGRNYGYEDY (SEQ ID NO:63), light chain CDR1 comprises KASQSVDYDGDSYMN (SEQ ID NO:64), light chain CDR2 comprises AASDLES (SEQ ID NO:65), and light chain CDR3 comprises QQANEDPRT (SEQ ID NO:66).

In certain embodiments of the methods described herein, the C3-binding agent comprises a heavy chain variable region and a light chain variable region, wherein the heavy chain variable region comprises heavy chain CDRs 1, 2, and 3 of an amino acid sequence set forth in SEQ ID NO:101, and the light chain variable region comprises light chain CDRs 1, 2, and 3 of an amino acid sequence set forth in SEQ ID NO:102. In certain embodiments, heavy chain CDR1 comprises GFTFSNYAMS (SEQ ID NO:67), heavy chain CDR2 comprises QTISSGGRYTYYPDSVKG (SEQ ID NO:68), heavy chain CDR3 comprises RYYGNSYWYFDV (SEQ ID NO:69), light chain CDR1 comprises KSSQSLLNSGNQKHYLT (SEQ ID NO:70), light chain CDR2 comprises GASTRGS (SEQ ID NO:71), and light chain CDR3 comprises QNDHSYPYT (SEQ ID NO:72).

In certain embodiments of the methods described herein, the C3-binding agent comprises a heavy chain variable region and a light chain variable region, wherein the heavy chain variable region comprises heavy chain CDRs 1, 2, and 3 of an amino acid sequence set forth in SEQ ID NO:103, and the light chain variable region comprises light chain CDRs 1, 2, and 3 of an amino acid sequence set forth in SEQ ID NO:104. In certain embodiments, heavy chain CDR1 comprises GFTFSSYTMS (SEQ ID NO:73), heavy chain CDR2 comprises YISSGGGTTYYPDTVKG (SEQ ID NO:74), heavy chain CDR3 comprises RYYRGSSLWYFDV (SEQ ID NO:75), light chain CDR1 comprises KSSQSLFNSGSQKNFLT (SEQ ID NO:76), light chain CDR2 comprises WASTRES (SEQ ID NO:77), and light chain CDR3 comprises QNDYSYPLT (SEQ ID NO:78).

In certain embodiments of the methods described herein, the C3-binding agent comprises a heavy chain variable region and a light chain variable region, wherein the heavy chain variable region comprises heavy chain CDRs 1, 2, and 3 of an amino acid sequence set forth in SEQ ID NO:105, and the light chain variable region comprises light chain CDRs 1, 2, and 3 of an amino acid sequence set forth in SEQ ID NO:106. In certain embodiments, heavy chain CDR1 comprises GYSITSGYSLH (SEQ ID NO:79), heavy chain CDR2 comprises YIHYSGSTNYNPSLKS (SEQ ID NO:80), heavy chain CDR3 comprises AWDYLDY (SEQ ID NO:81), light chain CDR1 comprises RASENIYSQLA (SEQ ID NO:82), light chain CDR2 comprises DAKTLAE (SEQ ID NO:83), and light chain CDR3 comprises HHHFGILYT (SEQ ID NO:84).

In certain embodiments of the methods described herein, the C3-binding agent comprises a heavy chain variable region and a light chain variable region, wherein the heavy chain variable region comprises heavy chain CDRs 1, 2, and 3 of an amino acid sequence set forth in SEQ ID NO:107, and the light chain variable region comprises light chain CDRs 1, 2, and 3 of an amino acid sequence set forth in SEQ ID NO:108. In certain embodiments, heavy chain CDR1 comprises GYSITSGYYWN (SEQ ID NO:85), heavy chain CDR2 comprises YIRYDGSNNYNPSLKN (SEQ ID NO:86), heavy chain CDR3 comprises HYGYDGGAFDF (SEQ ID NO:87), light chain CDR1 comprises RTSENIYNYLV (SEQ ID NO:88), light chain CDR2 comprises NAKTLEE (SEQ ID NO:89), and light chain CDR3 comprises QHHYGTPFT (SEQ ID NO:90).

In certain embodiments of the methods described herein, the C3-binding agent comprises a dsscFv comprising a heavy chain variable region and a light chain variable region. In certain embodiments, the heavy chain variable region comprises an amino acid sequence set forth in SEQ ID NO:110 or SEQ ID NO:111, and the light chain variable region comprises an amino acid sequence set forth in SEQ ID NO:112. In certain embodiments, the dsscFv comprises an amino acid sequence of SEQ ID NO:113. In certain embodiments, the dsscFv comprises an amino acid sequence of SEQ ID NO:114. In certain embodiments, the dsscFv comprises an amino acid sequence of SEQ ID NO:119. In certain embodiments, the dsscFv comprises an amino acid sequence of SEQ ID NO:229.

In some embodiments of the methods described herein, a method comprises administering a C3-binding agent (e.g., an antibody) described herein in combination with at least one additional therapeutic agent or therapeutic therapy. Treatment with two or more therapeutic agents often uses agents that work by different mechanisms of action, although this is not required. Combination therapy using agents with different mechanisms of action may result in additive or synergetic effects. Combination therapy may allow for a lower dose of each agent than is used in monotherapy, thereby reducing toxic side effects and/or increasing the therapeutic index of the agent(s). Combination therapy may decrease the likelihood that resistance to an agent will develop.

In some embodiments, the combination of a C3-binding agent (e.g., an antibody) described herein and at least one additional therapeutic agent results in additive or synergistic results. In some embodiments, the combination therapy results in an increase in the therapeutic index of the C3-binding agent. In some embodiments, the combination therapy results in an increase in the therapeutic index of the additional therapeutic agent(s). In some embodiments, the combination therapy results in a decrease in the toxicity and/or side effects of the C3-binding agent. In some embodiments, the combination therapy results in a decrease in the toxicity and/or side effects of the additional therapeutic agent(s).

In some embodiments, a combination treatment comprises one additional therapeutic agent or two or more additional therapeutic agents. In some embodiments, treatment with a C3-binding agent can occur prior to, concurrently with, or subsequent to administration of the additional therapeutic agents. In some embodiments, combined administration includes co-administration, either in a single pharmaceutical formulation or using separate formulations, or consecutive administration in either order but generally within a time period such that all active agents can exert their biological activities. In some embodiments, preparation of agents and/or dosing schedules for additional therapeutic agents are according to manufacturers' instructions or as determined empirically by the skilled practitioner.

In some embodiments of the methods described herein, a C3-binding agent (e.g., an antibody) is administered to a subject (e.g., a human) as part of a combination therapy. In some embodiments, the combination therapy comprises photodynamic therapy. In some embodiments, the combination therapy comprises photodynamic therapy with verteporfin. In some embodiments, a C3-binding agent (e.g., an antibody) is administered to a subject (e.g., a human), wherein the subject is administered one or more additional therapeutic agents. In some embodiments, an additional therapeutic agent is compstatin or an analog or derivative of compstatin (e.g., POT-4; APL-2). In some embodiments, an additional therapeutic agent is a C5 inhibitor. In some embodiments, a C5 inhibitor is selected from the group including, but not limited to, eculizumab, LFG316, or Zimura (anti-C5 aptamer). In some embodiments, an additional therapeutic agent is a properdin inhibitor (e.g., an anti-properdin antibody). In some embodiments, an additional therapeutic agent is a Factor D inhibitor. In some embodiments, a Factor D inhibitor is an anti-Factor D antibody (e.g., lampalizumab). In some embodiments, an additional therapeutic agent is a VEGF inhibitor. In some embodiments, a VEGF inhibitor is selected from the group including, but not limited to, pegaptanib (MACUGEN), ranibizumab (LUCENTIS), bevacizumab (AVASTIN), aflibercept (EYLEA), brolucizumab, and OPT-302. In some embodiments, an additional therapeutic agent is a PDGF inhibitor. In some embodiments, an additional therapeutic agent is a corticosteroid. In some embodiments, an additional therapeutic agent is a neuroprotective agent. In some embodiments, a neuroprotective agent is selected from the group including, but not limited to, ciliary neurotrophic factor (CNTF), tandospirone, and brimonidine.

It will be appreciated that the combination of a C3-binding agent (e.g., an antibody) described herein and at least one additional therapeutic agent may be administered in any order or concurrently. In some embodiments, a C3-binding agent is administered to subjects (e.g., humans) that have previously undergone treatment with a therapeutic agent. In some embodiments, a C3-binding agent and a second therapeutic agent are administered substantially simultaneously or concurrently. For example, a subject (e.g., a human) may be given a C3-binding agent while undergoing a course of treatment with a second therapeutic agent (e.g., an angiogenesis inhibitor). In some embodiments, a C3-binding agent is administered within 1 year of the treatment with a second therapeutic agent. In some embodiments, a C3-binding agent is administered within 10, 8, 6, 4, or 2 months of any treatment with a second therapeutic agent. In some embodiments, a C3-binding agent is administered within 4, 3, 2, or 1 weeks of any treatment with a second therapeutic agent. In some embodiments, a C3-binding agent is administered within 5, 4, 3, 2, or 1 days of any treatment with a second therapeutic agent. It will further be appreciated that the two (or more) agents or treatments can be administered to the subject within a matter of hours or minutes (i.e., substantially simultaneously).

For the treatment of a disease, the appropriate dosage of a C3-binding agent (e.g., an antibody) of the present disclosure depends on the disorder or disease to be treated, the severity and course of the disorder or disease, the responsiveness of the disorder or disease, whether the agent is administered for therapeutic or preventative purposes, previous therapy, the patient's clinical history, and so on. A C3-binding agent can be administered one time or over a series of treatments lasting from several days to several months, or until a cure is effected or a diminution of the disease state is achieved.

The dose of a C3-binding agent (e.g., an antibody) described herein may vary depending on the nature and/or severity of the disease or disorder, as well as the condition of the subject. In some embodiments, the dose of a C3-binding agent depends on the site of administration (e.g., into the vitreous cavity). In some embodiments, the dose of a C3-binding agent depends on the delivery system (e.g., eye drops). In some embodiments, a dose of a C3-binding agent (e.g., an antibody) described herein is from about 0.1 mg to about 20 mg. In some embodiments, a dose of a C3-binding agent (e.g., an antibody) described herein is from about 0.1 mg to about 20 mg into the vitreous cavity. In some embodiments, a dose of a C3-binding agent (e.g., an antibody) described herein is from about 0.1 mg to about 20 mg delivered by eye drop. In some embodiments, a dose of a C3-binding agent described herein is from about 1.0 mg to about 10 mg. In some embodiments, a dose of a C3-binding agent described herein is about 0.1, 0.25, 0.5, 1.0, 1.25, 2.0, 2.5, 3.0, 4.0, 5.0, 6.0, 7.0, 7.5, 8.0, 9.0, 10.0, 11.0, 12.0, 12.5, 13.0, 14.0, or 15 mg into the vitreous cavity. In some embodiments, a dose of a C3-binding agent described herein is about 0.1, 0.25, 0.5, 1.0, 1.25, 2.0, 2.5, 3.0, 4.0, 5.0, 6.0, 7.0, 7.5, 8.0, 9.0, 10.0, 11.0, 12.0, 12.5, 13.0, 14.0, or 15 mg delivered by eye drop.

In some embodiments, the C3-binding agent (e.g., an antibody) described herein is dosed once a month, once every 2 months, or once every 3 months. In some embodiments, the C3-binding agent is dosed once a month. In some embodiments, the C3-binding agent is dosed once every 6 weeks. In some embodiments, the C3-binding agent is dosed once every 2 months. In some embodiments, the C3-binding agent is dosed once every 10 weeks. In some embodiments, the C3-binding agent is dosed once every 3 months.

In some embodiments, the C3-binding agent (e.g., an antibody) is dosed using a 30 gauge needle. In some embodiments, the C3-binding agent is dosed using a 30+ gauge needle. In some embodiments, the C3-binding agent is injected in a formulation of about 25 to about 100 uL (per an eye). In some embodiments, the C3-binding agent is injected in a formulation of about 50 uL (per an eye). In some embodiments, the C3-binding agent is injected in a formulation of about 75 uL (per an eye). In some embodiments, the C3-binding agent is injected in a formulation of about 100 uL (per an eye).

In some embodiments, the C3-binding agent (e.g., an antibody) is delivered by eye drops. In some embodiments, the C3-binding agent is delivered in a formulation of about 25 to about 100 uL (per an eye). In some embodiments, the C3-binding agent is delivered in a formulation of about 50 uL (per an eye). In some embodiments, the C3-binding agent is delivered in a formulation of about 75 uL (per an eye). In some embodiments, the C3-binding agent is delivered in a formulation of about 100 uL (per an eye).

In some embodiments, the C3-binding agent (e.g., an antibody) is delivered topically. In certain embodiments of topical administration, the C3-binding agent (e.g., an antibody) is administered in combination with a cell penetrating peptide. In certain embodiments, the C3-binding agent (e.g., an antibody) and the cell penetrating peptide are delivered as part of a single pharmaceutical composition. Cell penetrating peptides are known in the art (see, e.g., de Cogan et al., 2017, Investigative Opthamology & Visual Science, 58(5):2578-2590). Nonlimiting examples of cell penetrating peptides are described in US Patent Publication Nos. 2019/0015521, 2017/0355730, 2018/0346531, and 2012/0065124.

The present disclosure provides compositions comprising a C3-binding agent (e.g., an antibody) described herein. The present disclosure also provides pharmaceutical compositions comprising a C3-binding agent described herein and a pharmaceutically acceptable vehicle.

Formulations are prepared for storage and use by combining a purified antibody or agent of the present disclosure with a pharmaceutically acceptable vehicle (e.g., a carrier or excipient). Those of skill in the art generally consider pharmaceutically acceptable carriers, excipients, and/or stabilizers to be inactive ingredients of a formulation or pharmaceutical composition.

Suitable pharmaceutically acceptable vehicles include, but are not limited to, nontoxic buffers such as phosphate, citrate, and other organic acids; salts such as sodium chloride; antioxidants including ascorbic acid and methionine; preservatives such as octadecyldimethylbenzyl ammonium chloride, hexamethonium chloride, benzalkonium chloride, benzethonium chloride, phenol, butyl or benzyl alcohol, alkyl parabens, such as methyl or propyl paraben, catechol, resorcinol, cyclohexanol, 3-pentanol, and m-cresol; low molecular weight polypeptides (e.g., less than about 10 amino acid residues); proteins such as serum albumin, gelatin, or immunoglobulins; hydrophilic polymers such as polyvinylpyrrolidone; amino acids such as glycine, glutamine, asparagine, histidine, arginine, or lysine; carbohydrates such as monosaccharides, disaccharides, glucose, mannose, or dextrins; chelating agents such as EDTA; sugars such as sucrose, mannitol, trehalose or sorbitol; salt-forming counter-ions such as sodium; metal complexes such as Zn-protein complexes; and non-ionic surfactants such as TWEEN or polyethylene glycol. (Remington: The Science and Practice of Pharmacy, 22^(nd) Edition, 2012, Pharmaceutical Press, London.). In some embodiments, the formulation is in the form of an aqueous solution. In some embodiments, the formulation is stored in a lyophilized or in an alternative dried form.

The binding agents of the present disclosure can be formulated in any suitable form for delivery to a target cell/tissue. In some embodiments, a C3-binding agent (e.g., an antibody) can be formulated as a liposome, microparticle, microcapsule, albumin microsphere, microemulsion, nano-particle, nanocapsule, or macroemulsion. In some embodiments, the pharmaceutical formulation includes an agent of the present disclosure complexed with liposomes. Methods to produce liposomes are known to those of skill in the art. For example, some liposomes can be generated by reverse phase evaporation with a lipid composition comprising phosphatidylcholine, cholesterol, and PEG-derivatized phosphatidylethanolamine (PEG-PE).

In some embodiments, a C3-binding agent (e.g., an antibody) is formulated as a sustained-release preparation. Suitable examples of sustained-release preparations include semi-permeable matrices of solid hydrophobic polymers containing an agent, where the matrices are in the form of shaped articles (e.g., films or microcapsules). Sustained-release matrices include but are not limited to polyesters, hydrogels such as poly(2-hydroxyethyl-methacrylate) or poly(vinyl alcohol), polylactides, copolymers of L-glutamic acid and 7 ethyl-L-glutamate, non-degradable ethylene-vinyl acetate, degradable lactic acid-glycolic acid copolymers such as the LUPRON DEPOT™ (injectable microspheres composed of lactic acid-glycolic acid copolymer and leuprolide acetate), sucrose acetate isobutyrate, and poly-D-(−)-3-hydroxybutyric acid.

The pharmaceutical compositions or formulations of the present disclosure can be administered in any number of ways for either local or systemic treatment. Administration can be topical by epidermal or transdermal patches, ointments, lotions, creams, gels, drops, suppositories, sprays, liquids and powders; pulmonary by inhalation or insufflation of powders or aerosols, including by nebulizer, intratracheal, and intranasal; oral; or parenteral including intravenous, intraarterial, intratumoral, subcutaneous, intraperitoneal, intramuscular (e.g., injection or infusion), intracranial (e.g., intrathecal or intraventricular), ocular, intraocular, or intravitreal.

In some embodiments of the methods described herein, a C3-binding agent (e.g., an antibody) described herein is administered by ocular injection. In some embodiments of the methods described herein, a C3-binding agent is administered by intraocular injection. In some embodiments of the methods described herein, a C3-binding agent is administered by intravitreal injection.

EXAMPLES Example 1 Generation of Antibodies

Anti-C3 antibodies were generated using human C3 as the immunogen. Single cell suspensions of lymphocytes were obtained from the spleens and lymph nodes of immunized mice after the individual animals had been determined to have suitable antibody titers. Lymphocytes were fused with murine myeloma cells by standard methods. Cells were dispersed into 96-well plates in HAT-containing selection media. Cell supernatants (approximately 10,000) were screened by ELISA for binding to human C3 and cyno C3. Approximately 1600 cell clones were selected based on binding assay results.

Example 2 C3 Alternative Pathway Biochemical Assay

Anti-C3 antibodies identified in C3 binding assays were tested for their ability to inhibit the in vitro generation of C3a. C3a is produced by the cleavage of C3 by the C3 convertase complex. The C3a assay was based upon a previously described method (Loyet et al., 2014, J Pharmacol and Exp Ther; 351:527-537). Briefly, 20 μL of solution of 50 nM human C3 (Complement Technologies) in GVB (bovine skin gelatin in veronal buffer) was mixed with 20 μL test anti-C3 antibodies or controls diluted in GVB for 10 minutes. Controls included (i) no C3; (ii) no Factor B and Factor D; (iii) no inhibitor; and (iv) compstatin as positive control. 100 nM human Factor B and human 100 nM Factor D (Complement Technologies) in 0.05 M EGTA/0.1 M MgCl2/GVB were added to the C3/Ab samples and the mixtures were incubated for an additional 10 minutes. 20 uL of 50% rabbit serum (diluted 1:2 in GVB) was added and incubated for 10 minutes, followed by addition of 20 μL of 0.5M EDTA to quench the reaction. The addition of rabbit serum cleaves C3a produced by C3 convertase in the reaction mixtures to C3a des Arg (C3a des Arg has been found to be more stable than C3a). C3 des Arg concentrations were subsequently measured by ELISA. Briefly, a mouse anti-C3a/C3a des Arg antibody (ThermoFisher) was coated on ELISA plates at 1.0 μg/mL and incubated overnight at 4° C. The following day, the plates were washed and 60 uL of SuperBlock blocking buffer (Pierce) was added to the plates and incubated for 60 minutes at room temperature. Prior to adding samples, blocking buffer was decanted from the wells. Samples from the C3/Ab reactions were diluted, added to the plates, and incubated for 90 minutes. The plates were washed, biotinylated anti-human C3/C3a/C3a des Arg antibody (Biolegend) was added to the wells (0.5 μg/mL), and the plates were incubated for 60 minutes. The plates were washed, 20 uL poly-HRP streptavidin (Pierce) was added to each well and the plates were incubated for 30 minutes. For detection, SuperSignal PICO ELISA chemiluminescent substrate (ThermoFisher Scientific) was added to each well. The plates were read in a luminometer with a 0.2 second read time per well at 425 nm.

Under these assay conditions, test anti-C3 antibodies were ranked for their ability to inhibit C3a des Arg production. Several dozen exemplary antibodies were observed to strongly inhibit C3 cleavage and C3a release. The activities of three exemplary antibodies, 38G10, 3D8, and 15C12, at concentrations ranging from 0.1 to 1000 nM, are shown in FIG. 1 .

Example 3 Alternative and Classical Pathway-Dependent Hemolysis Assays

Hemolytic assays have traditionally been used to assess the functional activity of the complement system. For the alternative pathway (AP) assay, rabbit erythrocytes were included with C3-depleted human serum and 50 nM of human C3 in the presence of increasing concentrations of anti-C3 antibodies 38G10, 3D8, and 15C12. For the classical pathway (CP), IgM-coated sheep erythrocytes were incubated with C3-depleted human serum and increasing concentration of anti-C3 antibodies 38G10, 3D8, and 15C12 in the presence of 10 nM human C3. Hemolysis was determined by reading the absorbance of the supernatant at 412 nm. Results were expressed as a percentage of hemolysis observed in control samples without any inhibitor and can be calculated into IC50s. These assays were duplicated using cyno serum as a source of C3.

Results of the AP and CP assays using human C3 and cyno C3 for a set of exemplary antibodies are summarized in Table 11 (IC₅₀) and shown in FIG. 2 for antibodies 38G10, 3D8, and 15C12 (% hemolysis).

TABLE 11 Hemolytic Assay IC₅₀ (nM) Antibody Human AP Human CP Cyno AP Cyno CP 3D8 4.2 3.6 5.5 ND 3G8 6.8 10.4 20.9 102.5 15C12 3.7 3.8 8.8 ND 27A8 8.5 7.6 9.6 ND 28C3 8.0 6.5 7.8 3.4 38F5 9.2 6.7 12.9 2.3 38G10 1.9 1.7 3.5 ND 62B11 6.6 4.2 ~11.0 ~1.0 62F2 5.7 5.0 8.7 5.3 63A3 6.5 4.1 3.4 1.6 ND-Not determined

These results showed that the anti-C3 antibodies inhibited activation of both the alternative and classical pathways as demonstrated by the inhibition of hemolysis.

Example 4 Binding Affinity

The binding affinities of exemplary anti-C3 antibodies to human C3 and cyno C3 were measured using a Biacore system (GE Healthcare LifeSciences). Briefly, anti-Fc antibody (Sigma-Aldrich) was immobilized on all four flow cells of a CM5 chip using amine coupling reagents (GE Healthcare LifeSciences). Antibodies were captured on flow cells 2, 3, and 4 using flow cell 1 as a reference. Concentrations ranging from 0.62-40 nM of human C3 or cyno C3 were injected at a flow rate of 50 L/min at 37° C. Kinetic data were collected over time and fit using the simultaneous global fit equation to yield affinity constants (K_(D) values) for each antibody.

Table 12 shows the binding affinities for antibodies 38G10, 3D8, and 15C12.

TABLE 12 Binding Affinity K_(D) (nM) Antibody Human C3 Cyno C3 38G10 0.19 0.16 3D8 1.90 1.40 15C12 0.13 0.13

Example 5 Binding Profile

The anti-C3 antibodies described herein were characterized for their ability to bind a number of other components of the complement cascade. Antibodies were screened for binding to C3, C3a, C3b, C3c, C3d, iC3b, and Factor Bb. A representative set of the results is shown in Table 13. All the anti-C3 antibodies included in Table 13 were able to block complement activation. The data are relative to the binding of the negative control mIgG2 antibody.

TABLE 13 Factor C3 C3a C3b C3c C3d iC3b Bb 3D8 0.47 −0.01 0.38 0.17 0.01 0.29 −0.01 3G8 0.37 −0.01 0.33 0.22 0.00 0.25 0.00 28C3 0.66 0.11 0.09 0.28 0.01 0.01 0.00 38F5 0.83 0.00 0.66 0.45 0.01 0.45 −0.01 38G10 0.53 0.02 0.06 0.13 0.00 0.06 0.01 62B11 0.83 −0.03 0.76 0.49 −0.02 0.54 −0.02 62F2 0.7 −0.04 0.61 0.43 0.01 0.49 0.00 63A3 0.95 −0.02 0.83 0.55 0.01 0.72 0.00 Control 0.00 0.00 0.00 0.00 0.00 0.00 0.00 mIgG2

These data indicated that antibody 38G10 had a unique C3 binding profile, in that it bound preferentially to C3 with no detectable or very limited binding to any of the fragments of the complement cascade.

Example 6 Sequence Analyses of Anti-C3 Antibodies

Antibodies 3D8, 3G8, 15C12, 27A8, 28C3, 38F5, 38G10, 62B11, 62F2, and 63A3 were sequenced and the heavy chain variable region and light chain variable region amino acid sequences are disclosed herein and summarized in Table 14.

TABLE 14 Heavy Chain Light Chain Antibody Variable Region Variable Region 3D8 SEQ ID NO: 91  SEQ ID NO: 92  3G8 SEQ ID NO: 93  SEQ ID NO: 94  15C12 SEQ ID NO: 95  SEQ ID NO: 96  27A8 SEQ ID NO: 97  SEQ ID NO: 98  28C3 SEQ ID NO: 99  SEQ ID NO: 100 38F5 SEQ ID NO: 101 SEQ ID NO: 102 38G10 SEQ ID NO: 18  SEQ ID NO: 19  62B11 SEQ ID NO: 103 SEQ ID NO: 104 62F2 SEQ ID NO: 105 SEQ ID NO: 106 63A3 SEQ ID NO: 107 SEQ ID NO: 108

The heavy chain and light chain CDRs for the individual antibodies are disclosed in Tables 1-10 and as SEQ ID NOs:7-12, 38-90, and 120-228.

Based on the antibody characterization data as well as additional studies, antibody 38G10 was selected for humanization (CDRs disclosed in Table 1A and heavy chain variable region and light chain variable region amino acid sequences disclosed herein as SEQ ID NO: 18 and SEQ ID NO: 19, respectively).

Example 7 Generation of Humanized Antibody

Antibody 38G10 was humanized by methods known to those skilled in the art and humanized 38G10 is referred to herein as Hz38G10. Antibody 38G10 was found to have a potential glycosylation site in CDR2 of the heavy chain variable region, YIYPHNGGTTYNQNFTG (SEQ ID NO:8). The consensus glycosylation site for N-linked glycans is N-X-S/T, wherein X can be any amino acid except proline. During the humanization process, the heavy chain CDR2 was reengineered to remove the glycosylation site resulting in antibody Hz38G10 comprising a heavy chain CDR2 comprising YIYPHNGGTTYNQQFTG (SEQ ID NO: 13). The heavy chain variable sequence of antibody Hz38G10 is SEQ ID NO:20 and the light chain variable sequence is SEQ ID NO:25; CDRs are disclosed in Table 1B.

Example 8 Characterization of Hz38G10

The binding affinity of Hz38G10 was determined using a Biacore system as described herein and compared with the binding affinity of the parental 38G10 antibody. Antibody Hz38G10 had a binding affinity to human C3 of 0.3 nM and to cyno C3 of 1.8 nM as compared to the parental antibody's binding affinity of approximately 0.1 nM to both human and cyno C3 (at 37° C.). These results demonstrated that the humanization process for antibody 38G10, as well as the removal of a glycosylation site within CDR2 of the heavy chain, did not have a significant effect on the binding capabilities to human C3 or cyno C3.

Hz38G10 was formulated in two different buffers and evaluated for viscosity at high concentrations. The first buffer formulation was 10 mM sodium phosphate, 40 mM sodium chloride, 0.03% polysorbate 20, and 5% sucrose at pH 6.2. Hz38G10 was concentrated to 164 mg/mL with a viscosity of 15.2 mPa-s (by RheoSense). The second buffer formulation was 10 mM histidine HCl, 10% α,α trehalose dihydrate, and 0.01% polysorbate 20 at pH 5.5. Hz38G10 was concentrated to 152 mg/mL with a viscosity of 17.6 mPa-s. These results demonstrated that Hz38G10 retained acceptable viscosity at high formulation concentrations.

Due to a lack of anti-C3 antibodies in the clinic or FDA-licensed, the binding affinity of Hz38G10 to human C3 was compared against compstatin, a 13-residue cyclic peptide with potent C3 inhibitory activity that was identified several years ago (Morikis et al., 1998, Protein Science; 7:619-627). More recently, a number of compstatin analogs and derivatives have been generated and studied. The binding affinity of Hz38G10 to human C3 was compared to the binding affinity of a compstatin derivative (referred to herein as “COMP”) and a pegylated version of the compstatin derivative (referred to herein as “COMP-PEG”). A Biacore system was used to assess the binding affinities of the different molecules to human C3. Binding affinity of Hz38G10 to human C3 at 25° C. and 37° C. was carried out as described in Example 4. Evaluation of COMP or COMP-PEG binding to human C3 was carried out as follows. Human C3 was immobilized on flow cell 2 of a CM5 chip using amine-coupling reagents (GE Healthcare LifeSciences) and flow cell 1 (immobilized with a similar amount of human IgG) was used as a reference. Concentrations ranging from 1.56-100 nM of COMP were injected at a flow rate of 50 μL/min for evaluation of binding affinity at 25° C. and 37° C. Similar experiments were set up with COMP-PEG (concentration range of 25-400 nM) for evaluation at 37° C. COMP-PEG binding to human C3 was also evaluated at 25° C. with modifications. Briefly, rat anti-PEG antibody (Abcam Inc.) was immobilized on a CM5 chip surface using amine coupling reagents and COMP-PEG was captured on flow cell 2. Human C3 (concentration range 12-100 nM) was injected at a flow rate of 50 μL/min. Kinetic data were collected over time and fit using the simultaneous global fit equation to yield affinity constants (K_(D) values) for each antibody.

A set of representative results is shown in Table 15.

TABLE 15 Hz38G10 COMP COMP-PEG K_(D) (25° C.), nM <0.1 7.1 55 K_(D) (37° C.), nM 0.28 21 490

These results suggest that antibody Hz38G10 binds to human C3 with a significantly greater affinity than a compstatin derivative or the pegylated version (ranging from approximately 50-80 times greater).

To confirm that the humanized version of antibody 38G10 retained the ability to inhibit complement activation, Hz38G10 was assessed in alternative and classical pathway-dependent hemolysis assays as described herein and compared to COMP and COMP-PEG. Hz38G10 and COMP or antibody Hz38G10 and COMP-PEG were tested for their respective abilities to inhibit hemolysis in the assays.

As shown in FIGS. 3 and 4 and Table 16, the results of these experiments indicated that antibody Hz38G10 was more effective at inhibiting complement activation than a compstatin derivative or a pegylated version of the compstatin derivative. Antibody Hz38G10 had similar inhibitory activity on both the classical and alternative pathways. In contrast, COMP and COMP-PEG appeared to have greater activity on the alternative pathway than the classical pathway. Antibody Hz38G10 was approximately 10-fold more effective than COMP or COMP-PEG in inhibiting the alternative pathway and approximately 40- to 60-fold more effective than the compstatin derivatives on inhibiting the classical pathway.

TABLE 16 Classical Pathway Alternative Pathway IC50 (nM) IC50 (nM) Hz38G10 2 2.5 COMP 90 23 Hz38G10 4.1 4.0 COMP-PEG 272 41.8

An additional experiment was undertaken to determine whether antibody Hz38G10 and the compstatin derivative (COMP) bound to the same or similar region on human C3. COMP was immobilized on a CM5 chip using amine coupling reagents (GE Healthcare LifeSciences) at a high density (approx. 3000 RUs). In separate reactions in a 96-well plate, human C3 (5 nM) was titrated with increasing concentrations of antibody Hz38G10 or COMP (0.05-100 nM). After an incubation of approximately 3 hours at room temperature, the C3-COMP or C3-Hz38G10 reactions were injected over the COMP-coated surface.

As shown in FIG. 5 , increasing concentrations of COMP reduced binding of C3 to COMP surface due to self-blocking (positive control). However, increasing concentration of Hz38G10 did not prevent C3 from binding to the COMP-coated chip surface. The results of this experiment indicated that antibody Hz38G10 and COMP bind different epitopes on human C3.

Example 9 Generation and Characterization of Hz38G10 Variants

Sequence analysis of the heavy chain CDRs of antibody Hz38G10 identified a potential spot for deamidation within CDR2, YIYPHNGGTTYNQQFTG (SEQ ID NO:13). An elevated pH stress test was performed at pH 8.5 and deamidation at the asparagine (N55 of SEQ ID NO:20) was determined to be 29.75% on Day 0 and 48.23% on Day 7 (an increase of 18.5%). A variant of antibody Hz38G10 was generated with a N55D mutation in the heavy chain CDR2, a change that would mimic a fully deamidated molecule. This antibody, Hz38G10(N55D), was assayed for binding to human C3 using a Biacore system as described herein and was shown to have reduced binding as compared to Hz38G10.

Four additional Hz38G10 variants were generated with amino acid substitutions within the heavy chain CDR2 at N55 or G56 of SEQ ID NO:20. The Hz38G10 variants contained (i) a N55E mutation, heavy chain CDR2 YIYPHEGGTTYNQQFTG (SEQ ID NO:16); (ii) a N55Q mutation, heavy chain CDR2 YIYPHQGGTTYNQQFTG (SEQ ID NO:17); (iii) a G56A mutation, heavy chain CDR2 YIYPHNAGTTYNQQFTG (SEQ ID NO:14); or (iv) a G56T mutation, heavy chain CDR2 YIYPHNTGTTYNQQFTG (SEQ ID NO:15). The heavy chain variable region sequence of antibody Hz38G10(G56A) is SEQ ID NO:21, Hz38G10(G56T) is SEQ ID NO:22, Hz38G10(N55E) is SEQ ID NO:23, and Hz38G10(N55Q) is SEQ ID NO:24; the light chain variable region sequence for all variants is SEQ ID NO:25; CDRs are disclosed in Table 1C.

These antibodies, Hz38G10(N55E), Hz38G10(N55Q), Hz38G10(G56A), and Hz38G10(G56T) were assayed for binding to human C3 using a Biacore system as described herein and compared to antibody Hz38G10. The results are shown in Table 17.

TABLE 17 Antibody Binding KD (nM) Hz38G10 0.30 Hz38G10(N55E) 6.20 Hz38G10(N55Q) 0.82 Hz38G10(G56A) 0.27 Hz38G10(G56T) 0.23

These results indicated that a mutation at position G56 retained binding affinity to a greater extent than a mutation at position N55.

To determine if the substitution of alanine for glycine at position 56 of the heavy chain variable region (SEQ ID NO:20) reduced deamidation within the CDR2, a pH stress test was performed with antibody Hz38G10(G56A) as described above. For this variant, deamidation at N55 of Hz38G10(G56A) (SEQ ID NO:21) was determined to be 0.66% on Day 0 and 1.0% on Day 7. These results showed that antibody Hz38G10(G56A) was very stable under deamidation stressed conditions.

To determine whether antibody Hz38G10(G56A) retained the ability to inhibit complement activation, the antibody was assessed in alternative and classical pathway hemolysis assays as described herein and compared to antibody Hz38G10. Hz38G10 and Hz38G10(G56A) were tested for their ability to inhibit hemolysis in the assays.

As shown in Table 18, antibody Hz38G10(G56A) showed almost identical inhibition activity when compared to antibody Hz38G10 for human C3 and cyno C3.

TABLE 18 Classical Pathway Alternative Pathway Antibody IC50 (nM) IC50 (nM) Human C3 Hz38G10 5.2 3.9 Hz38G10(G56A) 5.4 3.9 Cyno C3 Hz38G10 0.7 4.8 Hz38G10(G56A) 0.6 4.8

Example 10 Pharmacokinetics of Antibody Hz38G10

The pharmacokinetics (PK) of anti-C3 antibody Hz38G10 were assessed in New Zealand White rabbits at a dose of 1 mg or 7.5 mg. Antibody Hz38G10 was administered by intravitreal injection (IVT) as a single dose of 50 μL/eye. Samples were taken at 1 and 8 hours and on days 2, 4, 8, 15 and 22 (4 eyes/time point). The concentration of Hz38G10 was evaluated in the vitreous humor, aqueous humor, and retina.

As shown in Table 19, the half-life of Hz38G10 in the vitreous humor was approximately 4-5 days.

TABLE 19 Hz38G10 Cmax AUC T_(1/2) Dose (ug/mL) (day ug/mL) (day) 1.0 mg 541 3140 4.1 7.5 mg 5680 33049 5.3

The PK of Hz38G10 is similar to the reported PKs of bevacizumab and aflibercept in vitreous humor of rabbits. In addition, the distribution of Hz38G10 to the retina was estimated to be approximately 20% of the vitreous humor for both Cmax and AUC.

Example 11

Generation of Hz38G10 scFv

A scFv version of an exemplary anti-C3 antibody was generated. scFv molecules based on the heavy chain variable region (VH) and the light chain variable region (VL) of Hz38G10 were designed in two orientations and with or without disulfide stabilization. The four molecules were (i) VL-linker-VH scFv, (ii) VH-linker-VL scFv, (iii) VL-linker-VH dsscFv; and (iv) VH-linker-VL dsscFv, wherein dsscFv indicates a scFv with an engineered disulfide bond between the VL and VH regions. These four molecules were tested in an E. coli expression system and based on several parameters, for example, expression titer and percent monomer, the VL-linker-VH dsscFv molecule was selected for additional studies and characterization. The sequence of Hz38G10 dsscFv is disclosed herein as SEQ ID NO:113.

Hz38G10 dsscFv antibodies were produced via expression as inclusion bodies. BL21(DE3) E. coli were transformed with a plasmid encoding Hz38G10 VL-linker-VH dsscFv, referred to hereafter as Hz38G10 dsscFv. Transformed BL21(DE3) E. coli were harvested by low speed centrifugation. The bacterial pellet was resuspended by magnetic stirring in 50 mM Tris-HCl pH 7.5 for 15 minutes at room temperature. For cell disruption, the suspension was passed 3 times through a microfluidizer at 200 Bar. Inclusion bodies were recovered from broken cells by centrifugation at 4° C. in a fixed angle rotor operating at 13,000×g for 45 minutes. The resulting inclusion body pellet was washed with cold Milli-Q® water until the lipid and cell wall layers were removed. The washed inclusion body pellet was resuspended in 5 volumes of Milli-Q® water by magnetic stirring and collected by centrifugation at 13,000×g for 30 minutes. Washed inclusion bodies were solubilized in 10 volumes of 8 M guanidine-HCl, 50 mM Tris-HCl pH 7.5, 1 mM TCEP using magnetic stirring and incubated overnight at 4° C. The following day, a dounce homogenizer with loose pestle was used to resuspend any remaining solid inclusion body particles. Solubilized inclusion bodies were diluted dropwise 1:25 into refold buffer (3 M urea, 50 mM Tris-HCl pH 8.0, 160 mM L-arginine, 1 mM cysteine, 3 mM cystamine) under gentle magnetic stirring at room temperature to a final concentration of 0.1 mg/ml. Refolding was carried out for 48 hours at 4° C. and disulfide bond formation was monitored by SDS-PAGE under non-reducing conditions. The solution containing the refolded dsscFv was concentrated 5-fold by ultrafiltration/diafiltration (UF/DF) on a 0.22 m² 10,000 Da NMWCO tangential flow filtration membrane. The concentrate was cleared of misfolded dsscFv by rapid acidification to pH 2.8 with 4 volumes of 100 mM glycine pH 2.5. The solution was held at pH 2.8 as the solution was further concentrated 5-fold. After 15 minutes, the pH was quickly returned to neutral with addition of concentrated Tris-HCl solution. The resulting acid-treated solution was buffer-exchanged with diavolumes of Protein-L affinity binding buffer (50 mM Tris-HCl pH 7.5, 50 mM NaCl). Recovered diafilitration product was cleared of precipitate by centrifugation at 13,000×g for 45 minutes at 4° C. and subsequently filtered using a 0.2 pm membrane.

Hz38G10 dsscFv antibodies were purified in two chromatography steps: (i) a Protein L affinity column for capture and (ii) a cation exchange (CEX) column for polishing. For Protein L affinity chromatography, the suspension containing Hz38G10 dsscFv was applied to a 5 mL MiniChrom TOYOPEARL® AF-rProtein L-650F column (Tosoh Bioscience), washed extensively with Tris-buffered saline, and eluted with a step gradient of 100 mM glycine pH 2.5. The resulting elution pool (Pool M) was dialyzed against CEX binding buffer (20 mM sodium acetate pH 5.0). Dialyzed Pool M was applied to a HiTrap® SP HP cation exchange column (GE Healthcare), washed with 20 mM sodium acetate, pH 5.0, and eluted with an isocratic gradient of 50 sodium chloride in 20 mM sodium acetate, pH 5.0. Hz38G10 dsscFv-enriched fractions were pooled and evaluated by SDS-PAGE and analytical SEC methods. Subsequently, a Hz38G10(G56A) dsscFv antibody (SEQ ID NO:114) was generated following the same general methods.

Example 12

Characterization of Hz38G10 dsscFv

The solubility parameters of Hz38G10 dsscFv were investigated. The purified antibodies were dialyzed into buffer consisting of 10 mM sodium phosphate, 40 mM sodium chloride, 0.03% polysorbate 20, and 5% sucrose, pH 6.2. The solution was micro-concentrated using 10,000 Da NMWCO spin concentrator at 3,000×g at room temperature. Protein concentration was measured on an Agilent Cary 60 UV-VIS Solo VPE spectrophotometer. Protein concentration reached 229 mg/ml with no visible aggregation.

Hz38G10 dsscFv were compared to Hz38G10 intact antibody and a Fab version of Hz38G10 in several assays. Binding affinity to human C3 was assessed using a Biacore system as described herein. In addition, inhibition of the alternative pathway and classical pathway by the three antibodies was assessed in hemolysis assays as described herein.

The results are summarized in Table 20.

TABLE 20 Antibody AP human C3 CP human C3 Hz38G10 K_(D) (pM) IC₅₀ (nM) IC₅₀ (nM) Intact antibody 27 5.9 4.0 Fab ND 16 17.8 dsscFv 35 19.5 15.3

These results showed that Hz38G10 dsscFv had a similar K_(D) as compared to the intact antibody. In addition, Hz38G10 dsscFv had a similar level of inhibition of hemolytic activity in both the AP and CP pathways as compared to the intact antibody or the Fab version. It should be noted that the intact Hz38G10 antibody has two antigen-binding sites, while the Fab and dsscFv antibodies have only one antigen-binding site.

Example 13 In Vivo Inhibition of C3 Activation

To evaluate the ability of anti-C3 antibodies to block activation of C3 in the eye, Hz38G10 was tested in an LPS-induced complement activation model in cynomolgus monkeys. In normal cynomolgus monkeys, C3 activation is minimal and thus the inhibitory effects of an anti-C3 antibody on C3 activation cannot be reliably evaluated in this setting. It is known that LPS can activate the complement system and a pilot study confirmed that complement C3 was activated by intravitreal injection (IVT) of LPS. Using this LPS-induced C3 activation model, the effects of Hz38G10 on activation of C3 was evaluated.

Twelve normal female cynomolgus monkeys (ages ranging from 8 to 17 years old) were assigned to 2 groups with 6 animals per group. A baseline sampling of aqueous humor was conducted on Day −3. On Day 1, animals were treated in both eyes with a single IVT dose of either vehicle or Hz38G10 at 5 mg/eye at a dose volume of 67 μl/eye. On Day 3, animals were injected intravitreously with LPS at 30 ng/eye at a volume of 50 μl/eye. On Days 5, 8, 13, and 18 aqueous humor samples were taken. C3a concentrations in the aqueous humor were determined using a Complement C3a Human ELISA Kit (Invitrogen) following the manufacturer's instructions.

As shown in FIG. 6 , LPS induced a significant increase of C3a in the aqueous humor in both groups of animals as compared to baseline (Day −3). Significantly lower levels of C3a were observed in the Hz38G10-treated animals as compared to animals treated with vehicle.

These results demonstrate that an anti-C3 antibody is capable of functionally inhibiting complement activation in the eye.

Although the foregoing present disclosure has been described in some detail by way of illustration and example for purposes of clarity of understanding, the descriptions and examples should not be construed as limiting the scope of the present disclosure. The embodiments of the present disclosure described herein are intended to be merely exemplary, and those skilled in the art will recognize numerous equivalents to the specific procedures described herein. All such equivalents are considered to be within the scope of the present disclosure and are covered by the embodiments.

All publications, patents, patent applications, internet sites, and accession numbers/database sequences including both polynucleotide and polypeptide sequences cited herein are hereby incorporated by reference in their entirety for all purposes to the same extent as if each individual publication, patent, patent application, internet site, or accession number/database sequence were specifically and individually indicated to be so incorporated by reference.

Following are sequences disclosed in the application. CDR sequences are listed in Tables 1-10.

Human C3 amino acid sequence with predicted signal sequence underlined (SEQ ID NO: 1) MGPTSGPSLLLLLLTHLPLALGSPMYSIITPNILRLESEETMVLEAHDAQGDVPVTVTVH DFPGKKLVLSSEKTVLTPATNHMGNVTFTIPANREFKSEKGRNKFVTVQATFGTQVVEKV VLVSLQSGYLFIQTDKTIYTPGSTVLYRIFTVNHKLLPVGRTVMVNIENPEGIPVKQDSL SSQNQLGVLPLSWDIPELVNMGQWKIRAYYENSPQQVESTEFEVKEYVLPSFEVIVEPTE KFYYIYNEKGLEVTITARFLYGKKVEGTAFVIFGIQDGEQRISLPESLKRIPIEDGSGEV VLSRKVLLDGVQNPRAEDLVGKSLYVSATVILHSGSDMVQAERSGIPIVTSPYQIHFTKT PKYFKPGMPFDLMVFVTNPDGSPAYRVPVAVQGEDTVQSLTQGDGVAKLSINTHPSQKPL SITVRTKKQELSEAEQATRTMQALPYSTVGNSNNYLHLSVLRTELRPGETLNVNELLRMD RAHEAKIRYYTYLIMNKGRLLKAGRQVREPGQDLVVLPLSITTDFIPSFRLVAYYTLIGA SGQREVVADSVWVDVKDSCVGSLVVKSGQSEDRQPVPGQQMTLKIEGDHGARVVLVAVDK GVFVLNKKNKLTQSKIWDVVEKADIGCTPGSGKDYAGVESDAGLTFTSSSGQQTAQRAEL QCPQPAARRRRSVQLTEKRMDKVGKYPKELRKCCEDGMRENPMRESCORRTRFISLGEAC KKVELDCCNYITELRRQHARASHLGLARSNLDEDIIAEENIVSRSEFPESWLWNVEDLKE PPKNGISTKLMNIFLKDSITTWEILAVSMSDKKGICVADPFEVTVMQDFFIDLRLPYSVV RNEQVEIRAVLYNYRQNQELKVRVELLHNPAFCSLATTKRRHQQTVTIPPKSSLSVPYVI VPLKTGLQEVEVKAAVYHHFISDGVRKSLKVVPEGIRMNKTVAVRTLDPERLGREGVQKE DIPPADLSDQVPDTESETRILLQGTPVAQMTEDAVDAERLKHLIVTPSGCGEQNMIGMTP TVIAVHYLDETEQWEKFGLEKROGALELIKKGYTQQLAFRQPSSAFAAFVKRAPSTWLTA YVVKVESLAVNLIAIDSQVLCGAVKWLILEKQKPDGVFQEDAPVIHQEMIGGLRNNNEKD MALTAFVLISLQEAKDICEEQVNSLPGSITKAGDFLEANYMNLQRSYTVAIAGYALAQMG RLKGPLLNKELTTAKDKNRWEDPGKQLYNVEATSYALLALLQLKDFDFVPPVVRWLNEQR YYGGGYGSTQATFMVFQALAQYQKDAPDHQELNLDVSLQLPSRSSKITHRIHWESASLLR SEETKENEGFTVTAEGKGQGTLSVVTMYHAKAKDQLTCNKFDLKVTIKPAPETEKRPQDA KNTMILEICTRYRGDQDATMSILDISMMTGFAPDTDDLKQLANGVDRYISKYELDKAFSD RNTLIIYLDKVSHSEDDCLAFKVHQYENVELIQPGAVKVYAYYNLEESCTRFYHPEKEDG KLNKLCRDELCRCAEENCFIQKSDDKVTLEERLDKACEPGVDYVYKTRLVKVQLSNDEDE YIMAIEQTIKSGSDEVQVGQQRTFISPIKCREALKLEEKKHYLMWGLSSDFWGEKPNLSY IIGKDTWVEHWPEEDECQDEENQKQCQDLGAFTESMVVFGCPN Human C3 amino acid sequence without predicted signal sequence (SEQ ID NO: 2) SPMYSIITPNILRLESEETMVLEAHDAQGDVPVTVTVHDFPGKKLVLSSEKTVLTPATNH MGNVTFTIPANREFKSEKGRNKFVTVQATFGTQVVEKVVLVSLOSGYLFIQTDKTIYTPG STVLYRIFTVNHKLLPVGRTVMVNIENPEGIPVKQDSLSSQNQLGVLPLSWDIPELVNMG QWKIRAYYENSPQQVESTEFEVKEYVLPSFEVIVEPTEKFYYIYNEKGLEVTITARFLYG KKVEGTAFVIFGIQDGEQRISLPESLKRIPIEDGSGEVVLSRKVLLDGVQNPRAEDLVGK SLYVSATVILHSGSDMVQAERSGIPIVTSPYQIHFTKTPKYFKPGMPFDLMVFVTNPDGS PAYRVPVAVQGEDTVQSLTQGDGVAKLSINTHPSQKPLSITVRTKKQELSEAEQATRTMQ ALPYSTVGNSNNYLHLSVLRTELRPGETLNVNELLRMDRAHEAKIRYYTYLIMNKGRLLK AGRQVREPGQDLVVLPLSITTDFIPSERLVAYYTLIGASGQREVVADSVWVDVKDSCVGS LVVKSGQSEDRQPVPGQQMTLKIEGDHGARVVLVAVDKGVFVLNKKNKLTQSKIWDVVEK ADIGCTPGSGKDYAGVESDAGLTFTSSSGQQTAQRAELQCPQPAARRRRSVOLTEKRMDK VGKYPKELRKCCEDGMRENPMRFSCQRRTRFISLGEACKKVELDCCNYITELRRQHARAS HLGLARSNLDEDIIAEENIVSRSEFPESWLWNVEDLKEPPKNGISTKLMNIFLKDSITTW EILAVSMSDKKGICVADPFEVTVMQDFFIDLRLPYSVVRNEQVEIRAVLYNYRQNQELKV RVELLHNPAFCSLATTKRRHQQTVTIPPKSSLSVPYVIVPLKTGLQEVEVKAAVYHHFIS DGVRKSLKVVPEGIRMNKTVAVRTLDPERLGREGVQKEDIPPADLSDQVPDTESETRILL QGTPVAQMTEDAVDAERLKHLIVTPSGCGEQNMIGMTPTVIAVHYLDETEQWEKFGLEKR QGALELIKKGYTQQLAFRQPSSAFAAFVKRAPSTWLTAYVVKVESLAVNLIAIDSQVLCG AVKWLILEKQKPDGVFQEDAPVIHQEMIGGLRNNNEKDMALTAFVLISLQEAKDICEEQV NSLPGSITKAGDFLEANYMNLQRSYTVAIAGYALAQMGRLKGPLLNKELTTAKDKNRWED PGKQLYNVEATSYALLALLQLKDFDFVPPVVRWLNEQRYYGGGYGSTQATFMVFQALAQY QKDAPDHQELNLDVSLQLPSRSSKITHRIHWESASLLRSEETKENEGFTVTAEGKGQGTL SVVTMYHAKAKDQLTCNKEDLKVTIKPAPETEKRPQDAKNTMILEICTRYRGDQDATMSI LDISMMTGFAPDTDDLKQLANGVDRYISKYELDKAFSDRNTLIIYLDKVSHSEDDCLAFK VHQYFNVELIQPGAVKVYAYYNLEESCTRFYHPEKEDGKLNKLCRDELCRCAEENCFIQK SDDKVTLEERLDKACEPGVDYVYKTRLVKVQLSNDFDEYIMAIEQTIKSGSDEVQVGQQR TFISPIKCREALKLEEKKHYLMWGLSSDFWGEKPNLSYIIGKDTWVEHWPEEDECQDEEN QKQCQDLGAFTESMVVFGCPN Human C3 and C3b beta chain (amino acids 23-667) (SEQ ID NO: 3) SPMYSIITPNILRLESEETMVLEAHDAQGDVPVTVTVHDFPGKKLVLSSEKTVLTPATNH MGNVTFTIPANREFKSEKGRNKFVTVQATFGTQVVEKVVLVSLQSGYLFIQTDKTIYTPG STVLYRIFTVNHKLLPVGRTVMVNIENPEGIPVKQDSLSSQNQLGVLPLSWDIPELVNMG QWKIRAYYENSPQQVESTEFEVKEYVLPSFEVIVEPTEKFYYIYNEKGLEVTITARFLYG KKVEGTAFVIFGIQDGEQRISLPESLKRIPIEDGSGEVVLSRKVLLDGVQNPRAEDLVGK SLYVSATVILHSGSDMVQAERSGIPIVTSPYQIHFTKTPKYFKPGMPFDLMVFVTNPDGS PAYRVPVAVQGEDTVQSLTQGDGVAKLSINTHPSQKPLSITVRTKKQELSEAEQATRTMQ ALPYSTVGNSNNYLHLSVLRTELRPGETLNVNELLRMDRAHEAKIRYYTYLIMNKGRLLK AGRQVREPGQDLVVLPLSITTDFIPSFRLVAYYTLIGASGQREVVADSVWVDVKDSCVGS LVVKSGQSEDRQPVPGQQMTLKIEGDHGARVVLVAVDKGVFVLNKKNKLTQSKIWDVVEK ADIGCTPGSGKDYAGVFSDAGLTFTSSSGQQTAQRAELQCPQPAA Human C3 alpha chain (amino acids 672-1663) (SEQ ID NO: 4) SVQLTEKRMDKVGKYPKELRKCCEDGMRENPMRFSCQRRTRFISLGEACKKVELDCCNYI TELRRQHARASHLGLARSNLDEDIIAEENIVSRSEFPESWLWNVEDLKEPPKNGISTKLM NIFLKDSITTWEILAVSMSDKKGICVADPFEVTVMQDEFIDLRLPYSVVRNEQVEIRAVL YNYRQNQELKVRVELLHNPAFCSLATTKRRHQQTVTIPPKSSLSVPYVIVPLKTGLQEVE VKAAVYHHFISDGVRKSLKVVPEGIRMNKTVAVRTLDPERLGREGVQKEDIPPADLSDQV PDTESETRILLQGTPVAQMTEDAVDAERLKHLIVTPSGCGEQNMIGMTPTVIAVHYLDET EQWEKFGLEKRQGALELIKKGYTQQLAFRQPSSAFAAFVKRAPSTWLTAYVVKVESLAVN LIAIDSQVLCGAVKWLILEKQKPDGVFQEDAPVIHQEMIGGLRNNNEKDMALTAFVLISL QEAKDICEEQVNSLPGSITKAGDFLEANYMNLQRSYTVAIAGYALAQMGRLKGPLLNKEL TTAKDKNRWEDPGKQLYNVEATSYALLALLQLKDFDFVPPVVRWLNEQRYYGGGYGSTQA TFMVFQALAQYQKDAPDHQELNLDVSLQLPSRSSKITHRIHWESASLLRSEETKENEGET VTAEGKGQGTLSVVTMYHAKAKDQLTCNKEDLKVTIKPAPETEKRPQDAKNTMILEICTR YRGDQDATMSILDISMMTGFAPDTDDLKQLANGVDRYISKYELDKAFSDRNTLIIYLDKV SHSEDDCLAFKVHQYENVELIQPGAVKVYAYYNLEESCTRFYHPEKEDGKLNKLCRDELC RCAEENCFIQKSDDKVTLEERLDKACEPGVDYVYKTRLVKVQLSNDEDEYIMAIEQTIKS GSDEVQVGQQRTFISPIKCREALKLEEKKHYLMWGLSSDFWGEKPNLSYIIGKDTWVEHW PEEDECQDEENQKQCQDLGAFTESMVVFGCPN Human C3b alpha chain (amino acids 749-1663) (SEQ ID NO: 5) SNLDEDIIAEENIVSRSEFPESWLWNVEDLKEPPKNGISTKLMNIFLKDSITTWEILAVS MSDKKGICVADPFEVTVMQDFFIDLRLPYSVVRNEQVEIRAVLYNYRQNQELKVRVELLH NPAFCSLATTKRRHQQTVTIPPKSSLSVPYVIVPLKTGLQEVEVKAAVYHHFISDGVRKS LKVVPEGIRMNKTVAVRTLDPERLGREGVQKEDIPPADLSDQVPDTESETRILLQGTPVA QMTEDAVDAERLKHLIVTPSGCGEQNMIGMTPTVIAVHYLDETEQWEKFGLEKRQGALEL IKKGYTQQLAFRQPSSAFAAFVKRAPSTWLTAYVVKVESLAVNLIAIDSQVLCGAVKWLI LEKQKPDGVFQEDAPVIHQEMIGGLRNNNEKDMALTAFVLISLQEAKDICEEQVNSLPGS ITKAGDFLEANYMNLQRSYTVAIAGYALAQMGRLKGPLLNKELTTAKDKNRWEDPGKQLY NVEATSYALLALLQLKDFDFVPPVVRWLNEQRYYGGGYGSTQATFMVFQALAQYQKDAPD HQELNLDVSLQLPSRSSKITHRIHWESASLLRSEETKENEGFTVTAEGKGQGTLSVVTMY HAKAKDQLTCNKEDLKVTIKPAPETEKRPQDAKNTMILEICTRYRGDQDATMSILDISMM TGFAPDTDDLKQLANGVDRYISKYELDKAFSDRNTLIIYLDKVSHSEDDCLAFKVHQYEN VELIQPGAVKVYAYYNLEESCTRFYHPEKEDGKLNKLCRDELCRCAEENCFIQKSDDKVT LEERLDKACEPGVDYVYKTRLVKVQLSNDEDEYIMAIEQTIKSGSDEVQVGQQRTFISPI KCREALKLEEKKHYLMWGLSSDFWGEKPNLSYIIGKDTWVEHWPEEDECQDEENQKQCQD LGAFTESMVVFGCPN Human C3a (amino acids 672-748) (SEQ ID NO: 6) SVQLTEKRMDKVGKYPKELRKCCEDGMRENPMRFSCQRRTRFISLGEACKKVELDCCNYI TELRRQHARASHLGLAR 38G10 Heavy chain CDR1 (SEQ ID NO: 7) GYTFTDFYMD 38G10 Heavy chain CDR2 (SEQ ID NO: 8) YIYPHNGGTTYNQNETG 38G10 Heavy chain CDR3 (SEQ ID NO: 9) RGGFDEDY 38G10 Light chain CDR1 (SEQ ID NO 10) KASENVDTYVS 38G10 Light chain CDR2 (SEQ ID NO: 11) GASNRYT 38G10 Light chain CDR3 (SEQ ID NO: 12) GQSHSYPLT Hz38G10 Heavy chain CDR2 (SEQ ID NO: 13) YIYPHNGGTTYNQQFTG Hz38G10 G56A Heavy chain CDR2 (SEQ ID NO: 14) YIYPHNAGTTYNQQFTG Hz38G10 G56T Heavy chain CDR2 (SEQ ID NO: 15) YIYPHNTGTTYNQQFTG Hz38G10 N55E Heavy chain CDR2 (SEQ ID NO: 16) YIYPHEGGTTYNQQFTG Hz38G10 N55Q Heavy chain CDR2 (SEQ ID NO: 17) YIYPHQGGTTYNQQFTG 38G10 Heavy chain variable region amino acid sequence (SEQ ID NO: 18) EVQLQQSGPELVKPGDSVKMSCKASGYTFTDFYMDWVKQSHGKSLEWIGYIYPHNGGTTY NQNFTGKATLTVDKSSNTAYMELHSLTSEDSAVYYCARRGGFDEDYWGQGTTLTVSS 38G10 Light chain variable region amino acid sequence (SEQ ID NO: 19) NIVMTQSPKSMSLSVGERVTLRCKASENVDTYVSWYQQKPEQSPKLLIYGASNRYTGVPD RFTGSGSATEFTLTISSVQAEDLVGYHCGQSHSYPLTFGAGTKLELK Hz38G10 Heavy chain variable region amino acid sequence (SEQ ID NO: 20) QVQLVQSGAEVKKPGASVKVSCKASGYTFTDFYMDWVRQAPGQRLEWMGYIYPHNGGTTY NQQFTGRVTITVDKSASTAYMELSSLRSEDTAVYYCARRGGFDEDYWGQGTLVTVSS Hz38G10(G56A) Heavy chain variable region amino acid sequence (SEQ ID NO: 21) QVQLVQSGAEVKKPGASVKVSCKASGYTFTDFYMDWVRQAPGQRLEWMGYIYPHNAGTTY NQQFTGRVTITVDKSASTAYMELSSLRSEDTAVYYCARRGGFDFDYWGQGTLVTVSS Hz38G10(G56T) Heavy chain variable region amino acid sequence (SEQ ID NO: 22) QVQLVQSGAEVKKPGASVKVSCKASGYTFTDFYMDWVRQAPGQRLEWMGYIYPHNTGTTY NQQFTGRVTITVDKSASTAYMELSSLRSEDTAVYYCARRGGFDEDYWGQGTLVTVSS Hz38G10(N55E) Heavy chain variable region amino acid sequence (SEQ ID NO: 23) QVQLVQSGAEVKKPGASVKVSCKASGYTFTDFYMDWVRQAPGQRLEWMGYIYPHEGGTTY NQQFTGRVTITVDKSASTAYMELSSLRSEDTAVYYCARRGGFDEDYWGQGTLVTVSS Hz38G10(N55Q) Heavy chain variable region amino acid sequence (SEQ ID NO: 24) QVQLVQSGAEVKKPGASVKVSCKASGYTFTDFYMDWVRQAPGQRLEWMGYIYPHQGGTTY NQQFTGRVTITVDKSASTAYMELSSLRSEDTAVYYCARRGGFDEDYWGQGTLVTVSS Hz38G10 Light chain variable region amino acid sequence (SEQ ID NO: 25) DIQMTQSPSSLSASVGDRVTITCKASENVDTYVSWYQQKPGKAPKLLIYGASNRYTGVPS RFSGSGSGTDFTFTISSLQPEDIATYHCGQSHSYPLTFGQGTKLEIK Hz38G10 Heavy chain amino acid sequence with signal sequence underlined (SEQ ID NO: 26) MDMRVPAQLLGLLLLWLRGARCQVQLVQSGAEVKKPGASVKVSCKASGYTFTDFYMDWVR QAPGQRLEWMGYIYPHNGGTTYNQQFTGRVTITVDKSASTAYMELSSLRSEDTAVYYCAR RGGFDFDYWGQGTLVTVSSASTKGPSVFPLAPSSKSTSGGTAALGCLVKDYFPEPVTVSW NSGALTSGVHTFPAVLQSSGLYSLSSVVTVPSSSLGTQTYICNVNHKPSNTKVDKKVEPK SCDKTHTCPPCPAPALAGGPSVELFPPKPKDTLMISRTPEVTCVVVDVSHEDPEVKENWY VDGVEVHNAKTKPREEQYNSTYRVVSVLTVLHQDWLNGKEYKCKVSNKALPAPIEKTISK AKGQPREPQVYTLPPSREEMTKNQVSLTCLVKGFYPSDIAVEWESNGQPENNYKTTPPVL DSDGSFFLYSKLTVDKSRWQQGNVFSCSVMHEALHNHYTQKSLSLSPGK Hz38G10 Heavy chain amino acid sequence without signal sequence (SEQ ID NO: 27) QVQLVQSGAEVKKPGASVKVSCKASGYTFTDFYMDWVRQAPGQRLEWMGYIYPHNGGTTY NQQFTGRVTITVDKSASTAYMELSSLRSEDTAVYYCARRGGFDEDYWGQGTLVTVSSAST KGPSVFPLAPSSKSTSGGTAALGCLVKDYFPEPVTVSWNSGALTSGVHTFPAVLQSSGLY SLSSVVTVPSSSLGTQTYICNVNHKPSNTKVDKKVEPKSCDKTHTCPPCPAPALAGGPSV FLFPPKPKDTLMISRTPEVTCVVVDVSHEDPEVKENWYVDGVEVHNAKTKPREEQYNSTY RVVSVLTVLHQDWLNGKEYKCKVSNKALPAPIEKTISKAKGQPREPQVYTLPPSREEMTK NQVSLTCLVKGFYPSDIAVEWESNGQPENNYKTTPPVLDSDGSFFLYSKLTVDKSRWQQG NVFSCSVMHEALHNHYTQKSLSLSPGK Hz38G10(G56A) Heavy chain amino acid sequence with signal sequence underlined (SEQ ID NO: 28) MDMRVPAQLLGLLLLWLRGARCQVQLVQSGAEVKKPGASVKVSCKASGYTFTDFYMDWVR QAPGQRLEWMGYIYPHNAGTTYNQQFTGRVTITVDKSASTAYMELSSLRSEDTAVYYCAR RGGFDFDYWGQGTLVTVSSASTKGPSVFPLAPSSKSTSGGTAALGCLVKDYFPEPVTVSW NSGALTSGVHTFPAVLQSSGLYSLSSVVTVPSSSLGTQTYICNVNHKPSNTKVDKKVEPK SCDKTHTCPPCPAPALAGGPSVELFPPKPKDTLMISRTPEVTCVVVDVSHEDPEVKENWY VDGVEVHNAKTKPREEQYNSTYRVVSVLTVLHQDWLNGKEYKCKVSNKALPAPIEKTISK AKGQPREPQVYTLPPSREEMTKNQVSLTCLVKGFYPSDIAVEWESNGQPENNYKTTPPVL DSDGSFFLYSKLTVDKSRWQQGNVFSCSVMHEALHNHYTQKSLSLSPGK Hz38G10(G56A) Heavy chain amino acid sequence without signal sequence (SEQ ID NO: 29) QVQLVQSGAEVKKPGASVKVSCKASGYTFTDFYMDWVRQAPGQRLEWMGYIYPHNAGTTY NQQFTGRVTITVDKSASTAYMELSSLRSEDTAVYYCARRGGFDEDYWGQGTLVTVSSAST KGPSVFPLAPSSKSTSGGTAALGCLVKDYFPEPVTVSWNSGALTSGVHTFPAVLQSSGLY SLSSVVTVPSSSLGTQTYICNVNHKPSNTKVDKKVEPKSCDKTHTCPPCPAPALAGGPSV FLFPPKPKDTLMISRTPEVTCVVVDVSHEDPEVKENWYVDGVEVHNAKTKPREEQYNSTY RVVSVLTVLHQDWLNGKEYKCKVSNKALPAPIEKTISKAKGQPREPQVYTLPPSREEMTK NQVSLTCLVKGFYPSDIAVEWESNGQPENNYKTTPPVLDSDGSFFLYSKLTVDKSRWQQG NVFSCSVMHEALHNHYTQKSLSLSPGK Hz38G10 Light chain amino acid sequence with signal sequence underlined (SEQ ID NO: 30) MDMRVPAQLLGLLLLWLRGARCDIQMTQSPSSLSASVGDRVTITCKASENVDTYVSWYQQ KPGKAPKLLIYGASNRYTGVPSRFSGSGSGTDFTFTISSLQPEDIATYHCGQSHSYPLTE GQGTKLEIKRTVAAPSVFIFPPSDEQLKSGTASVVCLLNNFYPREAKVQWKVDNALQSGN SQESVTEQDSKDSTYSLSSTLTLSKADYEKHKVYACEVTHQGLSSPVTKSENRGEC Hz38G10 Light chain amino acid sequence without signal sequence (SEQ ID NO: 31) DIQMTQSPSSLSASVGDRVTITCKASENVDTYVSWYQQKPGKAPKLLIYGASNRYTGVPS RFSGSGSGTDFTFTISSLQPEDIATYHCGQSHSYPLTFGQGTKLEIKRTVAAPSVFIFPP SDEQLKSGTASVVCLLNNFYPREAKVQWKVDNALQSGNSQESVTEQDSKDSTYSLSSTLT LSKADYEKHKVYACEVTHQGLSSPVTKSENRGEC Cynomolgus monkey C3 amino acid sequence with predicted signal sequence underlined (SEQ ID NO: 32) MGLTSGPSLLLLLLIHLPLALGTPMYSMITPNVLRLESEETVVLEAHDANGDVPVTVTVH DFPGKKLVLSSEKTVLTPATSHMGSVTIRIPANKEFKSEKGHNKFVTVQATFGAQVVEKV VLVSLQSGYLFIQTDKTIYTPGSTVLCRIFTVNHKLLPVGRTVVVNIENPDGIPVKQDSL SSQNQFGILPLSWDIPELVNMGQWKIRAYYENSPQQVESTEFEVKEYVLPSFEVIVEPTE KFYYIYNQKGLEVTITARFLYGKKVEGTAFVIFGIQDGEQRISLPESLKRIQIEDGSGDA VLSRKVLLDGVQNPRPEDLVGKSLYVSVTVILHSGSDMVQAERSGIPIVTSPYQIHFTKT PKYFKPGMPFDLMVFVTNPDGSPAYRVPVAVQGEDAVQSLTQGDGVAKLSINTHPSQKPL SITVRTKKRELSEAEQATRTMEAQPYSTVGNSNNYLHLSVPRAELRPGETLNVNELLRMD RTQEAKIRYYTYLIMNKGKLLKVGRQVREPGQDLVVLPLSITTDFIPSERLVAYYTLIGA NGQREVVADSVWVDVKDSCVGSLVVKSGQSEDRQPLPGQQMTLKIEGDHGARVGLVAVDK GVFVLNKKNKLTQSKIWDVVEKADIGCTPGSGKDYAGVESDAGLTFASSSGQQTAQRAEL QCPQPAARRRRSVQLAEKRMDKVGQYPKELRKCCEHGMRENPMRESCQRRTRYITLDEAC KKAFLDCCNYITELRRQHARASHLGLARSNLDEDIIAEENIVSRSEFPESWLWKIEELKE APKNGISTKLMNIFLKDSITTWEILAVSLSDKKGICVADPFEVTVMQDFFIDLRLPYSVV RNEQVEIRAVLYNYRQNQELKVRVELLHNPAFCSLATAKRRHQQTVTIPPKSSLSVPYVI VPLKTGQQEVEVKAAVYHFFISDGVRKSLKVVPEGIRMNKTVAVRTLDPERLGQEGVQRE DVPPADLSDQVPDTESETRILLQGTPVAQMTEDAIDAERLKHLIVTPSGCGEQNMITMTP TVIAVHYLDETEQWEKFGPEKRQGALELIKKGYTQQLAFRQPSSAFAAFLNRAPSTWLTA YVVKVESLAVNLIAIDSQVLCGAVKWLILEKQKPDGVFQEDAPVIHQEMTGGERNTNEKD MALTAFVLISLQEAKEICEEQVNSLPGSITKAGDFLEANYMNLQRSYTVAIAAYALAQMG RLKGPLLNKELTTAKDKNRWEEPGQQLYNVEATSYALLALLQLKDFDFVPPVVRWLNEQR YYGGGYGSTQATFMVFQALAQYQKDVPDHKELNLDVSLQLPSRSSKIIHRIHWESASLLR SEETKENEGFTVTAEGKGQGTLSVVTMYHAKAKGQLTCNKFDLKVTIKPAPETEKRPQDA KNTMILEICTRYRGDQDATMSILDISMMTGFVPDTDDLKQLANGVDRYISKYELDKAFSD RNTLIIYLDKVSHSEDDCIAFKVHQYENVELIQPGAVKVYAYYNLAESCTRFYHPEKEDG KLNKLCRDELCRCAEENCFIQKLDDKVTLEERLDKACEPGVDYVYKTRLVKAQLSNDEDE YIMAIEQIIKSGSDEVQVGQQRTFISPIKCREALKLEERKHYLMWGLSSDFWGEKPNLSY IIGKDTWVEHWPEEDECQDEENQKQCQDLGTFTENMVVFGCPN Cynomolgus monkey C3 amino acid sequence without predicted signal sequence (SEQ ID NO: 33) TPMYSMITPNVLRLESEETVVLEAHDANGDVPVTVTVHDFPGKKLVLSSEKTVLTPATSH MGSVTIRIPANKEFKSEKGHNKFVTVQATFGAQVVEKVVLVSLQSGYLFIQTDKTIYTPG STVLCRIFTVNHKLLPVGRTVVVNIENPDGIPVKQDSLSSQNQFGILPLSWDIPELVNMG QWKIRAYYENSPQQVESTEFEVKEYVLPSFEVIVEPTEKFYYIYNQKGLEVTITARFLYG KKVEGTAFVIFGIQDGEQRISLPESLKRIQIEDGSGDAVLSRKVLLDGVQNPRPEDLVGK SLYVSVTVILHSGSDMVQAERSGIPIVTSPYQIHFTKTPKYFKPGMPFDLMVFVTNPDGS PAYRVPVAVQGEDAVQSLTQGDGVAKLSINTHPSQKPLSITVRTKKRELSEAEQATRTME AQPYSTVGNSNNYLHLSVPRAELRPGETLNVNFLLRMDRTQEAKIRYYTYLIMNKGKLLK VGRQVREPGQDLVVLPLSITTDFIPSFRLVAYYTLIGANGQREVVADSVWVDVKDSCVGS LVVKSGQSEDRQPLPGQQMTLKIEGDHGARVGLVAVDKGVFVLNKKNKLTQSKIWDVVEK ADIGCTPGSGKDYAGVFSDAGLTFASSSGQQTAQRAELQCPQPAARRRRSVQLAEKRMDK VGQYPKELRKCCEHGMRENPMRFSCQRRTRYITLDEACKKAFLDCCNYITELRRQHARAS HLGLARSNLDEDIIAEENIVSRSEFPESWLWKIEELKEAPKNGISTKLMNIFLKDSITTW EILAVSLSDKKGICVADPFEVTVMQDFFIDLRLPYSVVRNEQVEIRAVLYNYRQNQELKV RVELLHNPAFCSLATAKRRHQQTVTIPPKSSLSVPYVIVPLKTGQQEVEVKAAVYHFFIS DGVRKSLKVVPEGIRMNKTVAVRTLDPERLGQEGVQREDVPPADLSDQVPDTESETRILL QGTPVAQMTEDAIDAERLKHLIVTPSGCGEQNMITMTPTVIAVHYLDETEQWEKFGPEKR QGALELIKKGYTQQLAFRQPSSAFAAFLNRAPSTWLTAYVVKVESLAVNLIAIDSQVLCG AVKWLILEKQKPDGVFQEDAPVIHQEMTGGERNTNEKDMALTAFVLISLQEAKEICEEQV NSLPGSITKAGDFLEANYMNLQRSYTVAIAAYALAQMGRLKGPLLNKELTTAKDKNRWEE PGQQLYNVEATSYALLALLQLKDFDFVPPVVRWLNEQRYYGGGYGSTQATFMVFQALAQY QKDVPDHKELNLDVSLQLPSRSSKIIHRIHWESASLLRSEETKENEGFTVTAEGKGQGTL SVVTMYHAKAKGQLTCNKEDLKVTIKPAPETEKRPQDAKNTMILEICTRYRGDQDATMSI LDISMMTGFVPDTDDLKQLANGVDRYISKYELDKAFSDRNTLIIYLDKVSHSEDDCIAFK VHQYFNVELIQPGAVKVYAYYNLAESCTRFYHPEKEDGKLNKLCRDELCRCAEENCFIQK LDDKVTLEERLDKACEPGVDYVYKTRLVKAQLSNDEDEYIMAIEQIIKSGSDEVQVGQQR TFISPIKCREALKLEERKHYLMWGLSSDFWGEKPNLSYIIGKDTWVEHWPEEDECQDEEN QKQCQDLGTFTENMVVFGCPN Human IgG1 constant region (SEQ ID NO: 34) ASTKGPSVFPLAPSSKSTSGGTAALGCLVKDYFPEPVTVSWNSGALTSGVHTFPAVLQSS GLYSLSSVVTVPSSSLGTQTYICNVNHKPSNTKVDKKVEPKSCDKTHTCPPCPAPELLGG PSVFLFPPKPKDTLMISRTPEVTCVVVDVSHEDPEVKENWYVDGVEVHNAKTKPREEQYN STYRVVSVLTVLHQDWLNGKEYKCKVSNKALPAPIEKTISKAKGQPREPQVYTLPPSREE MTKNQVSLTCLVKGFYPSDIAVEWESNGQPENNYKTTPPVLDSDGSFFLYSKLTVDKSRW QQGNVFSCSVMHEALHNHYTQKSLSLSPGK Human IgG1 constant region E233A/L235A (SEQ ID NO: 35) ASTKGPSVFPLAPSSKSTSGGTAALGCLVKDYFPEPVTVSWNSGALTSGVHTFPAVLQSS GLYSLSSVVTVPSSSLGTQTYICNVNHKPSNTKVDKKVEPKSCDKTHTCPPCPAPALAGG PSVFLFPPKPKDTLMISRTPEVTCVVVDVSHEDPEVKENWYVDGVEVHNAKTKPREEQYN STYRVVSVLTVLHQDWLNGKEYKCKVSNKALPAPIEKTISKAKGQPREPQVYTLPPSREE MTKNQVSLTCLVKGFYPSDIAVEWESNGQPENNYKTTPPVLDSDGSFFLYSKLTVDKSRW QQGNVFSCSVMHEALHNHYTQKSLSLSPGK Human IgG1 constant region L234A/L235A (SEQ ID NO: 36) ASTKGPSVFPLAPSSKSTSGGTAALGCLVKDYFPEPVTVSWNSGALTSGVHTFPAVLQSS GLYSLSSVVTVPSSSLGTQTYICNVNHKPSNTKVDKKVEPKSCDKTHTCPPCPAPEAAGG PSVFLFPPKPKDTLMISRTPEVTCVVVDVSHEDPEVKENWYVDGVEVHNAKTKPREEQYN STYRVVSVLTVLHQDWLNGKEYKCKVSNKALPAPIEKTISKAKGQPREPQVYTLPPSREE MTKNQVSLTCLVKGFYPSDIAVEWESNGQPENNYKTTPPVLDSDGSFFLYSKLTVDKSRW QQGNVFSCSVMHEALHNHYTQKSLSLSPGK Rat C3 amino acid sequence with predicted signal sequence underlined (SEQ ID NO: 37) MGPTSGSQLLVLLLLLASSLLALGSPMYSIITPNVLRLESEETFILEAHDAQGDVPVTVT VQDFLKKQVLTSEKTVLTGATGHLNRVFIKIPASKEFNADKGHKYVTVVANFGATVVEKA VLVSFQSGYLFIQTDKTIYTPGSTVFYRIFTVDNNLLPVGKTVVIVIETPDGVPIKRDIL SSHNQYGILPLSWNIPELVNMGQWKIRAFYEHAPKQTFSAEFEVKEYVLPSFEVLVEPTE KFYYIHGPKGLEVSITARFLYGKNVDGTAFVIFGVQDEDKKISLALSLTRVLIEDGSGEA VLSRKVLMDGVRPSSPEALVGKSLYVSVTVILHSGSDMVEAERSGIPIVTSPYQIHFTKT PKFFKPAMPFDLMVFVTNPDGSPARRVPVVTQGSDAQALTQDDGVAKLSVNTPNNRQPLT ITVSTKKEGIPDARQATRTMQAQPYSTMHNSNNYLHLSVSRVELKPGDNLNVNFHLRTDA GQEAKIRYYTYLVMNKGKLLKAGRQVREPGQDLVVLSLPITPEFIPSFRLVAYYTLIGAN GQREVVADSVWVDVKDSCVGTLVVKGDPRDNRQPAPGHQTTLRIEGNQGARVGLVAVDKG VFVLNKKNKLTQSKIWDVVEKADIGCTPGSGKNYAGVEMDAGLTFKTNQGLQTDQREDPE CAKPAARRRRSVQLMERRMDKAGQYTDKGLRKCCEDGMRDIPMPYSCQRRARLITQGESC LKAFMDCCNYITKLREQHRRDHVLGLARSDVDEDIIPEEDIISRSHFPESWLWTIEELKE PEKNGISTKVMNIFLKDSITTWEILAVSLSDKKGICVADPYEITVMQDFFIDLRLPYSVV RNEQVEIRAVLFNYREQEKLKVRVELLHNPAFCSMATAKKRYYQTIEIPPKSSVAVPYVI VPLKIGLQEVEVKAAVENHFISDGVKKILKVVPEGMRVNKTVAVRTLDPEHLNQGGVQRE DVNAADLSDQVPDTDSETRILLQGTPVAQMAEDAVDGERLKHLIVTPSGCGEQNMIGMTP TVIAVHYLDQTEQWEKFGLEKRQEALELIKKGYTQQLAFKQPISAYAAFNNRPPSTWLTA MWSRSFSLAANLIAIDSQVLCGAVKWLILEKQKPDGVFQEDGPVIHQEMIGGERNTKEAD VSLTAFVLIALQEARDICEGQVNSLPGSINKAGEYLEASYLNLQRPYTVAIAGYALALMN KLEEPYLTKELNTAKDRNRWEEPGQQLYNVEATSYALLALLLLKDFDSVPPVVRWINDER YYGGGYGSTQATFMVFQALAQYRADVPDHKDLNMDVSLHLPSRSSPTVERLLWESGSLLR SEETKQNEGFSLTAKGKGQGTLSVVTVYHAKVKGKTTCKKFDLRVTIKPAPETAKKPQDA KSSMILDICTRYLGDVDATMSILDISMMTGFIPDTNDLELLSSGVDRYISKYEMDKAFSN KNTLIIYLEKISHSEEDCLSFKVHQFENVGLIQPGSVKVYSYYNLEESCTRFYHPEKDDG MLSKLCHNEMCRCAEENCFMHQSQDQVSLNERLDKACEPGVDYVYKTKLTTIELSDDEDE YIMTIEQVIKSGSDEVQAGQERRFISHVKCRNALKLQKGKQYLMWGLSSDLWGEKPNTSY IIGKDTWVEHWPEAEERQDQKNQKQCEDLGAFTETMVVFGCPN 3D8 Heavy chain variable region amino acid sequence (SEQ ID NO: 91) EIQLQQSGAELVKPGASVKISCKASGYSFTGYNMNWVKQSHGKSLEWIGNINPYYGSTNY NQKFKGKATLTVDKSSTTAYMQLDSLTSEDSAVYYCARGYYGGNYPFAYWGQGTLVTVSA 3D8 Light chain variable region amino acid sequence (SEQ ID NO: 92) DIQMTQSPASLSASVGETVTITCRASENIYSYLAWYQQKQGKSPQLLVYNAKTLAEGVPS RFSGSGSGTQFSLKINSLQPEDFGSYYCQHYYGTPYTFGGGSKVEIK 3G8 Heavy chain variable region amino acid sequence (SEQ ID NO: 93) EIQLQQSGAELVKPGASVKISCMASGYSFTGYNMNWVKQSHGKGLEWIGNINPYYDSTSY NQKFKGKATLTVDKSSSTAYMQLNSLTSEDSAVYYCARENYDFVGFAYWGQGTLVTVSA 3G8 Light chain variable region amino acid sequence (SEQ ID NO: 94) QIVLSQSPAILSASPGEKVTMTCRASSSVSYMHWFQQKPGSSPKPWIYVTSNLASGVPPR FSGSGSGTSYSLTISRVEAEDAATYYCQQWSTNPLTFGAGTKLELK 15C12 Heavy chain variable region amino acid sequence (SEQ ID NO: 95) EIQLQQSGAELEKPGASVKISCKASGYSFTGYNMHWVKQSHGKSLEWIGNINPYYGTTNS NQKFEDKATLTVDKSSSTAYMQLNSLTSEDSAVYYCARGIYYYGTGYPYFDFWGQGTTLT VSS 15C12 Light chain variable region amino acid sequence (SEQ ID NO: 96) DIQMTQTTSSLSASLGDRVTISCRASQDINNYLNWYLQKPDGTVKLLIYYTSRLHSGVPS RFSGSGSGTDYSLTISNLEQEDLATYFCQQGITLPWTFGGGTKLEIK 27A8 Heavy chain variable region amino acid sequence (SEQ ID NO: 97) QVQLLQPGAEFVKPGASVKLSCKASGYTFTDYWINWVKQRPGQGLEWIGNIYPGSTSANY NEKFKSKATLTIDTSSITAYMQLSSLTSDDSAVYYCARYGYDSWFAYWGQGTLVTVSA 27A8 Light chain variable region amino acid sequence (SEQ ID NO: 98) DVVLTQTPLSLPVNIGDQASISCKSTKSLLNSDGFTYLDWFLQKPGQSPHLLIYLVSNRF SGIPDRESGSGSETDFTLKISRVEAEDLGVYYCFQSNYLPLTFGSGTKLEIK 28C3 Heavy chain variable region amino acid sequence (SEQ ID NO: 99) QVQLQQSGPELVKPGASVKISCKASGYAFNSCWMNWVKQRPGKGLEWIGRIYPGDGDTNY NGKFKGKATLTADKSSTTAYMQLSSLTSEDSAVYFCAREGRNYGYEDYWGQGTTLTVSS 28C3 Light chain variable region amino acid sequence (SEQ ID NO: 100) DIVLTQSPASLAVSLGQRATISCKASQSVDYDGDSYMNWYQQKPGQPPKLLIYAASDLES GIPARFSGSGSGTDFTLNIHPVEEEDAATYYCQQANEDPRTFGGGTKLEIK 38F5 Heavy chain variable region amino acid sequence (SEQ ID NO: 101) EVMLVESGGALVKPGGSLKLSCTASGFTFSNYAMSWVRQTPEKRLEWVAQTISSGGRYTY YPDSVKGRFTISRDNARNTLYLQMSSLRSEDTAMYYCVRRYYGNSYWYFDVWGAGTTVTV SS 38F5 Light chain variable region amino acid sequence (SEQ ID NO: 102) DIVMTQSPSSLSVSAGEKVTMNCKSSQSLLNSGNQKHYLTWYQQKPGQPPKLLIYGASTR GSGVPDRFTGSGSGTDFTLTISSVQAEDLAVYYCQNDHSYPYTFGGGTKLEIK 62B11 Heavy chain variable region amino acid sequence (SEQ ID NO: 103) EVKLVESGGGLVQPGGSLKLSCAASGFTFSSYTMSWVRQTPEKRLEWVAYISSGGGTTYY PDTVKGRFTVSRDNAKNTLYLQMSSLRSEDTAMYSCARRYYRGSSLWYFDVWGAGTTVTV SS 62B11 Light chain variable region amino acid sequence (SEQ ID NO: 104) DIVMTQSPSSLTVTAGEKVTMSCKSSQSLENSGSQKNELTWYQQRPGQPPKLLIYWASTR ESGVPDRFTGSGSGTDFTLTISSVQAEDLAVYYCQNDYSYPLTFGAGTKLELK 62F2 Heavy chain variable region amino acid sequence (SEQ ID NO: 105) DVQLQESGPDLVKPSQSLSLTCTVTGYSITSGYSLHWIRQFPGNKLEWMGYIHYSGSTNY NPSLKSRISITRDTSKNQFFLKLNSVTSEDTATYHCARAWDYLDYWGQGTTLTVSS 62F2 Light chain variable region amino acid sequence (SEQ ID NO: 106) DIQMTQSPASLSASVGETVTITCRASENIYSQLAWYQQKQGKSPQLLVYDAKTLAEGVPS RFSGSGSDTQFSLKIISLQPEDFGRYYCHHHFGILYTFGGGTKLEMK 63A3 Heavy chain variable region amino acid sequence (SEQ ID NO: 107) DVQLQESGPGLVKPSQSLSLTCSVTGYSITSGYYWNWIRQFPGNKLEWMGYIRYDGSNNY NPSLKNRISITRDTSKNQVFLKLNSVTPEDTATYYCARHYGYDGGAFDFWGQGTTLTVSS 63A3 Light chain variable region amino acid sequence (SEQ ID NO: 108) DIQMTQSPASLSASVGETVTITCRTSENIYNYLVWYQQKQGKSPQLLVYNAKTLEEGVPS RFSGSGSGTQFSLKVNSLQPEDFGSYYCQHHYGTPFTFGSGTKLEIK Human IgG1 constant region L234A/L235A/P329G (SEQ ID NO: 109) ASTKGPSVFPLAPSSKSTSGGTAALGCLVKDYFPEPVTVSWNSGALTSGVHTFPAVLQSS GLYSLSSVVTVPSSSLGTQTYICNVNHKPSNTKVDKKVEPKSCDKTHTCPPCPAPEAAGG PSVFLFPPKPKDTLMISRTPEVTCVVVDVSHEDPEVKENWYVDGVEVHNAKTKPREEQYN STYRVVSVLTVLHQDWLNGKEYKCKVSNKALGAPIEKTISKAKGQPREPQVYTLPPSREE MTKNQVSLTCLVKGFYPSDIAVEWESNGQPENNYKTTPPVLDSDGSFFLYSKLTVDKSRW QQGNVFSCSVMHEALHNHYTQKSLSLSPGK Hz38G10 dsscFv heavy chain variable region (SEQ ID NO: 110) QVQLVQSGAEVKKPGASVKVSCKASGYTFTDFYMDWVRQAPGQCLEWMGYIYPHNGGTTY NQQFTGRVTITVDKSASTAYMELSSLRSEDTAVYYCARRGGFDEDYWGQGTLVTVSS Hz38G10(G56A) dsscFv heavy chain variable region (SEQ ID NO: 111) QVQLVQSGAEVKKPGASVKVSCKASGYTFTDFYMDWVRQAPGQCLEWMGYIYPHNAGTTY NQQFTGRVTITVDKSASTAYMELSSLRSEDTAVYYCARRGGFDEDYWGQGTLVTVSS Hz38G10 dsscFv light chain variable region (SEQ ID NO: 112) DIQMTQSPSSLSASVGDRVTITCKASENVDTYVSWYQQKPGKAPKLLIYGASNRYTGVPS RFSGSGSGTDFTFTISSLQPEDIATYHCGQSHSYPLTFGCGTKLEIK Hz38G10 dsscFv (SEQ ID NO: 113) MDIQMTQSPSSLSASVGDRVTITCKASENVDTYVSWYQQKPGKAPKLLIYGASNRYTGVP SRFSGSGSGTDFTFTISSLQPEDIATYHCGQSHSYPLTFGCGTKLEIKGGGGSGGGGSGG GGSQVQLVQSGAEVKKPGASVKVSCKASGYTFTDFYMDWVRQAPGQCLEWMGYIYPHNGG TTYNQQFTGRVTITVDKSASTAYMELSSLRSEDTAVYYCARRGGFDEDYWGQGTLVTVSS Hz38G10(G56A) dsscFv (SEQ ID NO: 114) MDIQMTQSPSSLSASVGDRVTITCKASENVDTYVSWYQQKPGKAPKLLIYGASNRYTGVP SRFSGSGSGTDFTFTISSLQPEDIATYHCGQSHSYPLTFGCGTKLEIKGGGGSGGGGSGG GGSQVQLVQSGAEVKKPGASVKVSCKASGYTFTDFYMDWVRQAPGQCLEWMGYIYPHNAG TTYNQQFTGRVTITVDKSASTAYMELSSLRSEDTAVYYCARRGGFDEDYWGQGTLVTVSS Linker (SEQ ID NO: 115) GGGGS Linker (SEQ ID NO: 116) GGGGSGGGGS Linker (SEQ ID NO: 117) GGGGSGGGGSGGGGS Linker (SEQ ID NO: 118) GGGGSGGGGSGGGGSGGGGS Hz38G10 dsscFv (SEQ ID NO: 119) DIQMTQSPSSLSASVGDRVTITCKASENVDTYVSWYQQKPGKAPKLLIYGASNRYTGVPS RFSGSGSGTDFTFTISSLQPEDIATYHCGQSHSYPLTFGCGTKLEIKGGGGSGGGGSGGG GSQVQLVQSGAEVKKPGASVKVSCKASGYTFTDFYMDWVRQAPGQCLEWMGYIYPHNGGT TYNQQFTGRVTITVDKSASTAYMELSSLRSEDTAVYYCARRGGFDEDYWGQGTLVTVSS Hz38G10(G56A) dsscFv (SEQ ID NO: 229) DIQMTQSPSSLSASVGDRVTITCKASENVDTYVSWYQQKPGKAPKLLIYGASNRYTGVPS RFSGSGSGTDFTFTISSLQPEDIATYHCGQSHSYPLTFGCGTKLEIKGGGGSGGGGSGGG GSQVQLVQSGAEVKKPGASVKVSCKASGYTFTDFYMDWVRQAPGQCLEWMGYIYPHNAGT TYNQQFTGRVTITVDKSASTAYMELSSLRSEDTAVYYCARRGGFDEDYWGQGTLVTVSS 

What is claimed:
 1. A binding agent that specifically binds human complement component C3 (C3), which comprises: (a) a heavy chain CDR1 comprising GYTFTDFYMD (SEQ ID NO:7); a heavy chain CDR2 comprising YIYPHNGGTTYNQNFTG (SEQ ID NO:8), YIYPHNGGTTYNQQFTG (SEQ ID NO:13), YIYPHNAGTTYNQQFTG (SEQ ID NO:14), YIYPHNTGTTYNQQFTG (SEQ ID NO:15), YIYPHEGGTTYNQQFTG (SEQ ID NO:16), or YIYPHQGGTTYNQQFTG (SEQ ID NO:17), and a heavy chain CDR3 comprising RGGFDFDY (SEQ ID NO:9); and/or (b) a light chain CDR1 comprising KASENVDTYVS (SEQ ID NO:10); a light chain CDR2 comprising GASNRYT (SEQ ID NO:11); and a light chain CDR3 comprising GQSHSYPLT (SEQ ID NO:12).
 2. The binding agent of claim 1, which comprises: (a) a heavy chain CDR1 comprising GYTFTDFYMD (SEQ ID NO:7); a heavy chain CDR2 comprising YIYPHNGGTTYNQNFTG (SEQ ID NO:8), and a heavy chain CDR3 comprising RGGFDFDY (SEQ ID NO:9); and/or (b) a light chain CDR1 comprising KASENVDTYVS (SEQ ID NO:10); a light chain CDR2 comprising GASNRYT (SEQ ID NO:11); and a light chain CDR3 comprising GQSHSYPLT (SEQ ID NO:12).
 3. The binding agent of claim 1, which comprises: (a) a heavy chain CDR1 comprising GYTFTDFYMD (SEQ ID NO:7); a heavy chain CDR2 comprising YIYPHNGGTTYNQQFTG (SEQ ID NO:13), and a heavy chain CDR3 comprising RGGFDFDY (SEQ ID NO:9); and/or (b) a light chain CDR1 comprising KASENVDTYVS (SEQ ID NO:10); a light chain CDR2 comprising GASNRYT (SEQ ID NO:11); and a light chain CDR3 comprising GQSHSYPLT (SEQ ID NO:12).
 4. The binding agent of claim 1, which comprises: (a) a heavy chain CDR1 comprising GYTFTDFYMD (SEQ ID NO:7); a heavy chain CDR2 comprising YIYPHNAGTTYNQQFTG (SEQ ID NO:14), and a heavy chain CDR3 comprising RGGFDFDY (SEQ ID NO:9); and/or (b) a light chain CDR1 comprising KASENVDTYVS (SEQ ID NO:10); a light chain CDR2 comprising GASNRYT (SEQ ID NO:11); and a light chain CDR3 comprising GQSHSYPLT (SEQ ID NO:12).
 5. The binding agent of claim 1, which comprises: (a) a heavy chain CDR1 comprising GYTFTDFYMD (SEQ ID NO:7); a heavy chain CDR2 comprising YIYPHNTGTTYNQQFTG (SEQ ID NO:15), and a heavy chain CDR3 comprising RGGFDFDY (SEQ ID NO:9); and/or (b) a light chain CDR1 comprising KASENVDTYVS (SEQ ID NO:10); a light chain CDR2 comprising GASNRYT (SEQ ID NO:11); and a light chain CDR3 comprising GQSHSYPLT (SEQ ID NO:12).
 6. The binding agent of claim 1, which comprises: (a) a heavy chain variable region having at least 90% sequence identity to SEQ ID NO:18, SEQ ID NO:20, SEQ ID NO:21, SEQ ID NO:22, SEQ ID NO:23, or SEQ ID NO:24 and/or (b) a light chain variable region having at least 90% sequence identity to SEQ ID NO:19 or SEQ ID NO:25.
 7. The binding agent of claim 6, which comprises a heavy chain variable region having at least 95% sequence identity to SEQ ID NO:18 and a light chain variable region having at least 95% sequence identity to SEQ ID NO:19.
 8. The binding agent of claim 6, which comprises a heavy chain variable region having at least 95% sequence identity to SEQ ID NO:20 and a light chain variable region having at least 95% sequence identity to SEQ ID NO:25.
 9. The binding agent of claim 6, which comprises a heavy chain variable region having at least 95% sequence identity to SEQ ID NO:21 and a light chain variable region having at least 95% sequence identity to SEQ ID NO:25.
 10. The binding agent of claim 6, which comprises a heavy chain variable region having at least 95% sequence identity to SEQ ID NO:22 and a light chain variable region having at least 95% sequence identity to SEQ ID NO:25.
 11. The binding agent of claim 6, which comprises a heavy chain variable region having at least 95% sequence identity to SEQ ID NO:23 and a light chain variable region having at least 95% sequence identity to SEQ ID NO:25.
 12. The binding agent of claim 6, which comprises a heavy chain variable region having at least 95% sequence identity to SEQ ID NO:24 and a light chain variable region having at least 95% sequence identity to SEQ ID NO:25.
 13. The binding agent of claim 6, which comprises a heavy chain variable region comprising SEQ ID NO:18 and a light chain variable region comprising SEQ ID NO:19.
 14. The binding agent of claim 6, which comprises a heavy chain variable region comprising SEQ ID NO:20 and a light chain variable region comprising SEQ ID NO:25.
 15. The binding agent of claim 6, which comprises a heavy chain variable region comprising SEQ ID NO:21 and a light chain variable region comprising SEQ ID NO:25.
 16. The binding agent of claim 6, which comprises a heavy chain variable region comprising SEQ ID NO:22 and a light chain variable region comprising SEQ ID NO:25.
 17. The binding agent of claim 6, which comprises a heavy chain variable region comprising SEQ ID NO:23 and a light chain variable region comprising SEQ ID NO:25.
 18. The binding agent of claim 6, which comprises a heavy chain variable region comprising SEQ ID NO:24 and a light chain variable region comprising SEQ ID NO:25.
 19. The binding agent of claim 1, which comprises a heavy chain variable region and a light chain variable region, wherein the heavy chain variable region comprises heavy chain CDRs 1, 2, and 3 of an amino acid sequence set forth in SEQ ID NO:18, and the light chain variable region comprises light chain CDRs 1, 2, and 3 of an amino acid sequence set forth in SEQ ID NO:19.
 20. The binding agent of claim 19, wherein heavy chain CDR1 comprises GYTFTDFYMD (SEQ ID NO:7), heavy chain CDR2 comprises YIYPHNGGTTYNQNFTG (SEQ ID NO:8), heavy chain CDR3 comprises RGGFDFDY (SEQ ID NO:9), light chain CDR1 comprises KASENVDTYVS (SEQ ID NO:10), light chain CDR2 comprises GASNRYT (SEQ ID NO:11), and light chain CDR3 comprises GQSHSYPLT (SEQ ID NO:12).
 21. The binding agent of claim 1, which comprises a heavy chain variable region and a light chain variable region, wherein the heavy chain variable region comprises heavy chain CDRs 1, 2, and 3 of an amino acid sequence set forth in SEQ ID NO:20, and the light chain variable region comprises light chain CDRs 1, 2, and 3 of an amino acid sequence set forth in SEQ ID NO:25.
 22. The binding agent of claim 21, which comprises a heavy chain variable region and a light chain variable region, wherein heavy chain CDR1 comprises GYTFTDFYMD (SEQ ID NO:7), heavy chain CDR2 comprises YIYPHNGGTTYNQQFTG (SEQ ID NO:13), heavy chain CDR3 comprises RGGFDFDY (SEQ ID NO:9), light chain CDR1 comprises KASENVDTYVS (SEQ ID NO:10), light chain CDR2 comprises GASNRYT (SEQ ID NO:11), and light chain CDR3 comprises GQSHSYPLT (SEQ ID NO:12).
 23. The binding agent of claim 1, which comprises a heavy chain variable region and a light chain variable region, wherein the heavy chain variable region comprises heavy chain CDRs 1, 2, and 3 of an amino acid sequence set forth in SEQ ID NO:21, and the light chain variable region comprises light chain CDRs 1, 2, and 3 of an amino acid sequence set forth in SEQ ID NO:25.
 24. The binding agent of claim 23, wherein heavy chain CDR1 comprises GYTFTDFYMD (SEQ ID NO:7), heavy chain CDR2 comprises YIYPHNAGTTYNQQFTG (SEQ ID NO:14), heavy chain CDR3 comprises RGGFDFDY (SEQ ID NO:9), light chain CDR1 comprises KASENVDTYVS (SEQ ID NO:10), light chain CDR2 comprises GASNRYT (SEQ ID NO:11), and light chain CDR3 comprises GQSHSYPLT (SEQ ID NO:12).
 25. The binding agent of claim 1, which comprises a heavy chain variable region and a light chain variable region, wherein the heavy chain variable region comprises heavy chain CDRs 1, 2, and 3 of an amino acid sequence set forth in SEQ ID NO:22, and the light chain variable region comprises light chain CDRs 1, 2, and 3 of an amino acid sequence set forth in SEQ ID NO:25.
 26. The binding agent of claim 25, wherein heavy chain CDR1 comprises GYTFTDFYMD (SEQ ID NO:7), heavy chain CDR2 comprises YIYPHNTGTTYNQQFTG (SEQ ID NO:15), heavy chain CDR3 comprises RGGFDFDY (SEQ ID NO:9), light chain CDR1 comprises KASENVDTYVS (SEQ ID NO:10), light chain CDR2 comprises GASNRYT (SEQ ID NO:11), and light chain CDR3 comprises GQSHSYPLT (SEQ ID NO:12).
 27. The binding agent of claim 1, which comprises a heavy chain variable region and a light chain variable region, wherein the heavy chain variable region comprises heavy chain CDRs 1, 2, and 3 of an amino acid sequence set forth in SEQ ID NO:23, and the light chain variable region comprises light chain CDRs 1, 2, and 3 of an amino acid sequence set forth in SEQ ID NO:25.
 28. The binding agent of claim 27, wherein heavy chain CDR1 comprises GYTFTDFYMD (SEQ ID NO:7), heavy chain CDR2 comprises YIYPHEGGTTYNQQFTG (SEQ ID NO:16), heavy chain CDR3 comprises RGGFDFDY (SEQ ID NO:9), light chain CDR1 comprises KASENVDTYVS (SEQ ID NO:10), light chain CDR2 comprises GASNRYT (SEQ ID NO:11), and light chain CDR3 comprises GQSHSYPLT (SEQ ID NO:12).
 29. The binding agent of claim 1, which comprises a heavy chain variable region and a light chain variable region, wherein the heavy chain variable region comprises heavy chain CDRs 1, 2, and 3 of an amino acid sequence set forth in SEQ ID NO:24, and the light chain variable region comprises light chain CDRs 1, 2, and 3 of an amino acid sequence set forth in SEQ ID NO:25.
 30. The binding agent of claim 29, wherein heavy chain CDR1 comprises GYTFTDFYMD (SEQ ID NO:7), heavy chain CDR2 comprises YIYPHQGGTTYNQQFTG (SEQ ID NO:17), heavy chain CDR3 comprises RGGFDFDY (SEQ ID NO:9), light chain CDR1 comprises KASENVDTYVS (SEQ ID NO:10), light chain CDR2 comprises GASNRYT (SEQ ID NO:11), and light chain CDR3 comprises GQSHSYPLT (SEQ ID NO:12).
 31. A binding agent that specifically binds human C3, which comprises a CDR1, CDR2, and CDR3 from a heavy chain variable region having the amino acid sequence of SEQ ID NO:18 and a CDR1, CDR2, and CDR3 from a light chain variable region having the amino acid sequence of SEQ ID NO:19.
 32. A binding agent that specifically binds human C3, which comprises a CDR1, CDR2, and CDR3 from a heavy chain variable region having the amino acid sequence of SEQ ID NO:20 and a CDR1, CDR2, and CDR3 from a light chain variable region having the amino acid sequence of SEQ ID NO:25.
 33. A binding agent that specifically binds human C3, which comprises a CDR1, CDR2, and CDR3 from a heavy chain variable region having the amino acid sequence of SEQ ID NO:21 and a CDR1, CDR2, and CDR3 from a light chain variable region having the amino acid sequence of SEQ ID NO:25.
 34. A binding agent that specifically binds human C3, which comprises a CDR1, CDR2, and CDR3 from a heavy chain variable region having the amino acid sequence of SEQ ID NO:22 and a CDR1, CDR2, and CDR3 from a light chain variable region having the amino acid sequence of SEQ ID NO:25.
 35. A binding agent that specifically binds human C3, which comprises a CDR1, CDR2, and CDR3 from a heavy chain variable region having the amino acid sequence of SEQ ID NO:23 and a CDR1, CDR2, and CDR3 from a light chain variable region having the amino acid sequence of SEQ ID NO:25.
 36. A binding agent that specifically binds human C3, which comprises a CDR1, CDR2, and CDR3 from a heavy chain variable region having the amino acid sequence of SEQ ID NO:24 and a CDR1, CDR2, and CDR3 from a light chain variable region having the amino acid sequence of SEQ ID NO:25.
 37. A binding agent that specifically binds human C3, which comprises a heavy chain comprising the amino acid sequence of SEQ ID NO:28 and a light chain comprising the amino acid sequence of SEQ ID NO:29.
 38. A binding agent that specifically binds human complement component C3 (C3), which comprises a heavy chain variable region and a light chain variable region, wherein the heavy chain variable region comprises heavy chain CDRs 1, 2, and 3 of an amino acid sequence set forth in SEQ ID NO:91, and the light chain variable region comprises light chain CDRs 1, 2, and 3 of an amino acid sequence set forth in SEQ ID NO:92.
 39. The binding agent of claim 38, wherein heavy chain CDR1 comprises GYSFTGYNMN (SEQ ID NO:38), heavy chain CDR2 comprises NINPYYGSTNYNQKFKG (SEQ ID NO:39), heavy chain CDR3 comprises GYYGGNYPFAY (SEQ ID NO:40), light chain CDR1 comprises RASENIYSYLA (SEQ ID NO:41), light chain CDR2 comprises NAKTLAE (SEQ ID NO:42), and light chain CDR3 comprises QHYYGTPYT (SEQ ID NO:43).
 40. A binding agent that specifically binds human complement component C3 (C3), which comprises a heavy chain variable region and a light chain variable region, wherein the heavy chain variable region comprises heavy chain CDRs 1, 2, and 3 of an amino acid sequence set forth in SEQ ID NO:93, and the light chain variable region comprises light chain CDRs 1, 2, and 3 of an amino acid sequence set forth in SEQ ID NO:94.
 41. The binding agent of claim 40, wherein heavy chain CDR1 comprises GYSFTGYNMN (SEQ ID NO:38), heavy chain CDR2 comprises NINPYYDSTSYNQKFKG (SEQ ID NO:44), heavy chain CDR3 comprises ENYDFVGFAY (SEQ ID NO:45), light chain CDR1 comprises RASSSVSYMH (SEQ ID NO:46), light chain CDR2 comprises VTSNLAS (SEQ ID NO:47), and light chain CDR3 comprises QQWSTNPLT (SEQ ID NO:48).
 42. A binding agent that specifically binds human complement component C3 (C3), which comprises a heavy chain variable region and a light chain variable region, wherein the heavy chain variable region comprises heavy chain CDRs 1, 2, and 3 of an amino acid sequence set forth in SEQ ID NO:95, and the light chain variable region comprises light chain CDRs 1, 2, and 3 of an amino acid sequence set forth in SEQ ID NO:96.
 43. The binding agent of claim 42, wherein heavy chain CDR1 comprises GYSFTGYNMH (SEQ ID NO:49), heavy chain CDR2 comprises NINPYYGTTNSNQKFED (SEQ ID NO:50), heavy chain CDR3 comprises GIYYYGTGYPYFDF (SEQ ID NO:51), light chain CDR1 comprises RASQDINNYLN (SEQ ID NO:52), light chain CDR2 comprises YTSRLHS (SEQ ID NO:53), and light chain CDR3 comprises QQGITLPWT (SEQ ID NO:54).
 44. A binding agent that specifically binds human complement component C3 (C3), which comprises a heavy chain variable region and a light chain variable region, wherein the heavy chain variable region comprises heavy chain CDRs 1, 2, and 3 of an amino acid sequence set forth in SEQ ID NO:97, and the light chain variable region comprises light chain CDRs 1, 2, and 3 of an amino acid sequence set forth in SEQ ID NO:98.
 45. The binding agent of claim 44, wherein heavy chain CDR1 comprises GYTFTDYWIN (SEQ ID NO:55), heavy chain CDR2 comprises NIYPGSTSANYNEKFKS (SEQ ID NO:56), heavy chain CDR3 comprises YGYDSWFAY (SEQ ID NO:57), light chain CDR1 comprises KSTKSLLNSDGFTYLD (SEQ ID NO:58), light chain CDR2 comprises LVSNRFS (SEQ ID NO:59), and light chain CDR3 comprises FQSNYLPLT (SEQ ID NO:60).
 46. A binding agent that specifically binds human complement component C3 (C3), which comprises a heavy chain variable region and a light chain variable region, wherein the heavy chain variable region comprises heavy chain CDRs 1, 2, and 3 of an amino acid sequence set forth in SEQ ID NO:99, and the light chain variable region comprises light chain CDRs 1, 2, and 3 of an amino acid sequence set forth in SEQ ID NO:100.
 47. The binding agent of claim 46, wherein heavy chain CDR1 comprises GYAFNSCWMN (SEQ ID NO:61), heavy chain CDR2 comprises RIYPGDGDTNYNGKFKG (SEQ ID NO:62), heavy chain CDR3 comprises EGRNYGYEDY (SEQ ID NO:63), light chain CDR1 comprises KASQSVDYDGDSYMN (SEQ ID NO:64), light chain CDR2 comprises AASDLES (SEQ ID NO:65), and light chain CDR3 comprises QQANEDPRT (SEQ ID NO:66).
 48. A binding agent that specifically binds human complement component C3 (C3), which comprises a heavy chain variable region and a light chain variable region, wherein the heavy chain variable region comprises heavy chain CDRs 1, 2, and 3 of an amino acid sequence set forth in SEQ ID NO:101, and the light chain variable region comprises light chain CDRs 1, 2, and 3 of an amino acid sequence set forth in SEQ ID NO:102.
 49. The binding agent of claim 48, wherein heavy chain CDR1 comprises GFTFSNYAMS (SEQ ID NO:67), heavy chain CDR2 comprises QTISSGGRYTYYPDSVKG (SEQ ID NO:68), heavy chain CDR3 comprises RYYGNSYWYFDV (SEQ ID NO:69), light chain CDR1 comprises KSSQSLLNSGNQKHYLT (SEQ ID NO:70), light chain CDR2 comprises GASTRGS (SEQ ID NO:71), and light chain CDR3 comprises QNDHSYPYT (SEQ ID NO:72).
 50. A binding agent that specifically binds human complement component C3 (C3), which comprises a heavy chain variable region and a light chain variable region, wherein the heavy chain variable region comprises heavy chain CDRs 1, 2, and 3 of an amino acid sequence set forth in SEQ ID NO:103, and the light chain variable region comprises light chain CDRs 1, 2, and 3 of an amino acid sequence set forth in SEQ ID NO:104.
 51. The binding agent of claim 50, wherein heavy chain CDR1 comprises GFTFSSYTMS (SEQ ID NO:73), heavy chain CDR2 comprises YISSGGGTTYYPDTVKG (SEQ ID NO:74), heavy chain CDR3 comprises RYYRGSSLWYFDV (SEQ ID NO:75), light chain CDR1 comprises KSSQSLFNSGSQKNFLT (SEQ ID NO:76), light chain CDR2 comprises WASTRES (SEQ ID NO:77), and light chain CDR3 comprises QNDYSYPLT (SEQ ID NO:78).
 52. A binding agent that specifically binds human complement component C3 (C3), which comprises a heavy chain variable region and a light chain variable region, wherein the heavy chain variable region comprises heavy chain CDRs 1, 2, and 3 of an amino acid sequence set forth in SEQ ID NO:105, and the light chain variable region comprises light chain CDRs 1, 2, and 3 of an amino acid sequence set forth in SEQ ID NO:106.
 53. The binding agent of claim 52, wherein heavy chain CDR1 comprises GYSITSGYSLH (SEQ ID NO:79), heavy chain CDR2 comprises YIHYSGSTNYNPSLKS (SEQ ID NO:80), heavy chain CDR3 comprises AWDYLDY (SEQ ID NO:81), light chain CDR1 comprises RASENIYSQLA (SEQ ID NO:82), light chain CDR2 comprises DAKTLAE (SEQ ID NO:83), and light chain CDR3 comprises HHHFGILYT (SEQ ID NO; 84).
 54. A binding agent that specifically binds human complement component C3 (C3), which comprises a heavy chain variable region and a light chain variable region, wherein the heavy chain variable region comprises heavy chain CDRs 1, 2, and 3 of an amino acid sequence set forth in SEQ ID NO:107, and the light chain variable region comprises light chain CDRs 1, 2, and 3 of an amino acid sequence set forth in SEQ ID NO:108.
 55. The binding agent of claim 54, wherein heavy chain CDR1 comprises GYSITSGYYWN (SEQ ID NO:85), heavy chain CDR2 comprises YIRYDGSNNYNPSLKN (SEQ ID NO:86), heavy chain CDR3 comprises HYGYDGGAFDF (SEQ ID NO:87), light chain CDR1 comprises RTSENIYNYLV (SEQ ID NO:88), light chain CDR2 comprises NAKTLEE (SEQ ID NO:89), and light chain CDR3 comprises QHHYGTPFT (SEQ ID NO:90).
 56. The binding agent of any one of claims 1-55, which is an antibody.
 57. The binding agent of any one of claims 1-56, which is a monoclonal antibody.
 58. The binding agent of any one of claims 1-57, which is a chimeric, humanized, or human antibody.
 59. The binding agent of any one of claims 1-58, which is a bispecific antibody or a multispecific antibody.
 60. The binding agent of any one of claims 56-59, which is an antibody fragment comprising at least one antigen-binding site.
 61. The binding agent of claim 56, which is a Fab, Fab′, F(ab′)₂, Fv, scFv, (scFv)₂, single chain antibody, dual variable region antibody, diabody, nanobody, or single variable region antibody.
 62. The binding agent of claim 56, which is a disulfide-linked scFv (dsscFv) comprising a heavy chain variable region and a light chain variable region.
 63. The binding agent of claim 62, wherein the heavy chain variable region comprises an amino acid sequence set forth in SEQ ID NO:110 or SEQ ID NO:111, and the light chain variable region comprises an amino acid sequence set forth in SEQ ID NO:112.
 64. The binding agent of claim 62, wherein the dsscFv comprises an amino acid sequence of SEQ ID NO:113, SEQ ID NO: 114, SEQ ID NO:119, or SEQ ID NO:229.
 65. The binding agent of any one of claims 60-64, wherein the binding agent is attached to a half-life extending moiety.
 66. The binding agent of any one of claims 56-59, which is an IgG1 antibody.
 67. The binding agent of any one of claims 56-59, which is an IgG2 antibody.
 68. The binding agent of any one of claims 56-59, which is an IgG4 antibody.
 69. A binding agent that specifically binds human complement component C3 (C3; SEQ ID NO:1), wherein the binding agent comprises a scaffold protein and a heavy chain CDR1, CDR2, and CDR3 and light chain CDR1, CDR2, and CDR3 from: (i) a heavy chain variable region comprising SEQ ID NO:18 and a light chain variable region comprising SEQ ID NO:19; (ii) a heavy chain variable region comprising SEQ ID NO:20 and a light chain variable region comprising SEQ ID NO:25; (iii) a heavy chain variable region comprising SEQ ID NO:21 and a light chain variable region comprising SEQ ID NO:25; or (iv) a heavy chain variable region comprising SEQ ID NO:22 and a light chain variable region comprising SEQ ID NO:25.
 70. The binding agent of any one of claims 1-69, which does not bind C3b at a detectable level.
 71. The binding agent of any one of claims 1-69, which binds C3 with an affinity that is at least 50-fold greater than the agent's affinity to C3b.
 72. The binding agent of any one of claims 1-69, which binds C3 with an affinity that is at least 100-fold greater than the agent's affinity to C3b.
 73. The binding agent of any one of claims 1-69, which is an antagonist of C3.
 74. The binding agent of any one of claims 1-73, which inhibits C3 activity.
 75. The binding agent of any one of claims 1-74, which inhibits complement activation.
 76. The binding agent of any one of claims 1-75, which inhibits activation of the classical complement pathway.
 77. The binding agent of any one of claims 1-75, which inhibits activation of the alternative complement pathway.
 78. The binding agent of any one of claims 1-75, which inhibits activation of the classical complement pathway and the alternative complement pathway.
 79. A binding agent that specifically binds human complement component C3 (C3; SEQ ID NO:1), which has at least one or more of the following properties: (a) binds to cyno C3 (e.g., SEQ ID NO:32); (b) inhibits C3 cleavage, (c) inhibits C3 cleavage and C3a release, (d) inhibits activation of the alternative complement pathway (e.g., as assessed by hemolytic assays), (e) inhibits activation of the classical complement pathway (e.g., as assessed by hemolytic assays), (f) inhibits activation of the alternative complement pathway and classical complement pathway (e.g., as assessed by hemolytic assays), (g) does not detectably bind to Factor Bb, (h) does not detectably bind to C3d, (i) does not detectably bind to C3a, (j) does not detectably bind to C3b, (k) does not detectably bind to iC3b, (l) does not detectably bind to Factor Bb and C3d, (m) does not detectably bind to Factor Bb, C3d, and C3a, (n) does not detectably bind to Factor Bb, C3d, C3a, C3b, and iC3b, (o) binds to human C3 with a greater affinity than compstatin, and (p) has a half-life of about 4-5 days in human vitreous humor.
 80. The binding agent of claim 79, which comprises: (a) a heavy chain CDR1 comprising SEQ ID NO:7, a heavy chain CDR2 comprising SEQ ID NO:8, a heavy chain CDR3 comprising SEQ ID NO:9, a light chain CDR1 comprising SEQ ID NO:10, a light chain CDR2 comprising SEQ ID NO:11, and a light chain CDR3 comprising SEQ ID NO:12; (b) a heavy chain CDR1 comprising SEQ ID NO:7, a heavy chain CDR2 comprising SEQ ID NO:13, a heavy chain CDR3 comprising SEQ ID NO:9, a light chain CDR1 comprising SEQ ID NO:10, a light chain CDR2 comprising SEQ ID NO:11, and a light chain CDR3 comprising SEQ ID NO:12; (c) a heavy chain CDR1 comprising SEQ ID NO:7, a heavy chain CDR2 comprising SEQ ID NO:14, a heavy chain CDR3 comprising SEQ ID NO:9, a light chain CDR1 comprising SEQ ID NO:10, a light chain CDR2 comprising SEQ ID NO:11, and a light chain CDR3 comprising SEQ ID NO:12; (d) a heavy chain CDR1 comprising SEQ ID NO:7, a heavy chain CDR2 comprising SEQ ID NO:15, a heavy chain CDR3 comprising SEQ ID NO:9, a light chain CDR1 comprising SEQ ID NO:10, a light chain CDR2 comprising SEQ ID NO:11, and a light chain CDR3 comprising SEQ ID NO:12; (e) a heavy chain CDR1 comprising SEQ ID NO:7, a heavy chain CDR2 comprising SEQ ID NO:16, a heavy chain CDR3 comprising SEQ ID NO:9, a light chain CDR1 comprising SEQ ID NO:10, a light chain CDR2 comprising SEQ ID NO:11, and a light chain CDR3 comprising SEQ ID NO:12; or (f) a heavy chain CDR1 comprising SEQ ID NO:7, a heavy chain CDR2 comprising SEQ ID NO:17, a heavy chain CDR3 comprising SEQ ID NO:9, a light chain CDR1 comprising SEQ ID NO:10, a light chain CDR2 comprising SEQ ID NO:11, and a light chain CDR3 comprising SEQ ID NO:12.
 81. The binding agent of claim 79, which comprises a heavy chain CDR1 comprising SEQ ID NO:7, a heavy chain CDR2 comprising SEQ ID NO: 14, a heavy chain CDR3 comprising SEQ ID NO:9, a light chain CDR1 comprising SEQ ID NO:10, a light chain CDR2 comprising SEQ ID NO:11, and a light chain CDR3 comprising SEQ ID NO:12.
 82. The binding agent of claim 79, which comprises: (a) a heavy chain variable region comprising SEQ ID NO:20 and a light chain variable region comprising SEQ ID NO:25; (b) a heavy chain variable region comprising SEQ ID NO:21 and a light chain variable region comprising SEQ ID NO:25; (c) a heavy chain variable region comprising SEQ ID NO:22 and a light chain variable region comprising SEQ ID NO:25; (d) a heavy chain variable region comprising SEQ ID NO:23 and a light chain variable region comprising SEQ ID NO:25; or (e) a heavy chain variable region comprising SEQ ID NO:24 and a light chain variable region comprising SEQ ID NO:25.
 83. The binding agent of claim 79, which comprises a heavy chain variable region comprising SEQ ID NO:21 and a light chain variable region comprising SEQ ID NO:25.
 84. The binding agent of any one of claims 79-83, which is an antibody.
 85. The binding agent of any one of claims 79-84, which is a monoclonal antibody.
 86. The binding agent of any one of claims 79-85, which is a chimeric, humanized, or human antibody.
 87. The binding agent of any one of claims 79-86, which is a bispecific antibody or a multispecific antibody.
 88. The binding agent of any one of claims 79-87, which is an antibody fragment comprising at least one antigen-binding site.
 89. The binding agent of claim 84, which is a Fab, Fab′, F(ab′)2, Fv, scFv, (scFv)2, single chain antibody, dual variable region antibody, diabody, nanobody, or single variable region antibody.
 90. The binding agent of claim 84, which is a disulfide-linked scFv (dsscFv).
 91. The binding agent of claim 89 or 90, wherein the binding agent is attached to a half-life extending moiety.
 92. The binding agent of any one of claims 84-87, which is an IgG1 antibody.
 93. The binding agent of any one of claims 84-87, which is an IgG2 antibody.
 94. The binding agent of any one of claims 84-87, which is an IgG4 antibody.
 95. A monoclonal antibody that specifically binds human complement component C3 (C3; SEQ ID NO:1), which comprises a heavy chain comprising the amino acid sequence of SEQ ID NO:28 and a light chain comprising the amino acid sequence of SEQ ID NO:29.
 96. An antibody that competes with the binding agent of any one of claims 1-94 for binding to human C3.
 97. A pharmaceutical composition that comprises the binding agent of any one of claims 1-94 and a pharmaceutically acceptable carrier.
 98. A pharmaceutical composition that comprises the monoclonal antibody of claim 95 and a pharmaceutically acceptable carrier.
 99. An isolated polynucleotide or polynucleotides encoding the binding agent of any one of claims 1-94.
 100. An isolated polynucleotide or polynucleotides encoding the monoclonal antibody of claim
 95. 101. A vector or vectors comprising the polynucleotide or polynucleotides of claim 99 or claim
 100. 102. An isolated cell comprising the polynucleotide or polynucleotides of claim 99 or claim
 100. 103. An isolated cell comprising the vector or vectors of claim
 101. 104. An isolated cell producing the binding agent of any one of claims 1-94 or the antibody of claim
 95. 105. A hybridoma that produces the monoclonal antibody of claim
 95. 106. A method of treating an eye disorder in a subject, the method comprising administering to the subject a therapeutically effective amount of the binding agent of any one of claims 1-94 or the monoclonal antibody of claim
 95. 107. The method of claim 106, wherein the eye disorder is selected from the group consisting of: macular degeneration, diabetic retinopathy, retinopathy of prematurity, macular dystrophy, retinal dystrophy, uveitis, keratitis, scleritis, retinitis pigmentosa, choroidal neovascularization, retinal neovascularization, and ocular inflammation.
 108. A method of treating age-related macular degeneration (AMD) in a subject, the method comprising administering to the subject a therapeutically effective amount of the binding agent of any one of claims 1-94 or the monoclonal antibody of claim
 95. 109. The method of claim 108, wherein the AMD is dry AMD.
 110. The method of claim 108, wherein the AMD is geographic atrophy.
 111. A method of inhibiting or suppressing drusen formation in an eye of a subject, the method comprising administering to an eye of the subject a therapeutically effective amount of the binding agent of any one of claims 1-94 or the monoclonal antibody of claim
 95. 112. A method of inhibiting or suppressing retinal pigment epithelium atrophy in an eye of a subject, the method comprising administering to an eye of the subject a therapeutically effective amount of the binding agent of any one of claims 1-94 or the monoclonal antibody of claim
 95. 113. A method of inhibiting complement activation in an eye of a subject, the method comprising administering to an eye of the subject a therapeutically effective amount of the binding agent of any one of claims 1-94 or the monoclonal antibody of claim
 95. 114. The method of any one of claims 106-113, wherein the binding agent or antibody is administered to an eye of the subject by ocular injection, intraocular injection, or intravitreal injection.
 115. The method of any one of claims 106-113, wherein the binding agent or antibody is administered to an eye of the subject by intravitreal injection.
 116. The method of any one of claims 106-113, wherein the binding agent or antibody is administered as part of a combination therapy.
 117. The method of claim 116, wherein the combination therapy comprises photodynamic therapy.
 118. The method of claim 116, wherein the combination therapy comprises at least one additional therapeutic agent.
 119. The method of claim 118, wherein the additional therapeutic agent is selected from the group consisting of: a VEGF inhibitor, a complement inhibitor, a PDGF inhibitor, and a steroid.
 120. The method of claim 118, wherein the additional therapeutic agent is a VEGF inhibitor.
 121. The method of claim 120, wherein the VEGF inhibitor is selected from the group consisting of: pegaptanib, ranibizumab, bevacizumab, aflibercept, and OPT-302.
 122. The method of any one of claims 106-121, wherein the subject is a human.
 123. Use of the binding agent of any one of claims 1-94 in the manufacture of a medicament for treatment of an eye disorder.
 124. The use of claim 123, wherein the eye disorder is selected from the group consisting of: macular degeneration, diabetic retinopathy, retinopathy of prematurity, macular dystrophy, retinal dystrophy, uveitis, keratitis, scleritis, retinitis pigmentosa, choroidal neovascularization, retinal neovascularization, and ocular inflammation.
 125. The use of claim 123, wherein the eye disorder is aged-related macular degeneration (AMD).
 126. The use of claim 125, wherein the AMD is dry AMD.
 127. The use of claim 125, wherein the AMD is geographic atrophy.
 128. Use of the monoclonal antibody of claim 95 in the manufacture of a medicament for treatment of an eye disorder.
 129. The use of claim 128, wherein the eye disorder is selected from the group consisting of: macular degeneration, diabetic retinopathy, retinopathy of prematurity, macular dystrophy, retinal dystrophy, uveitis, keratitis, scleritis, retinitis pigmentosa, choroidal neovascularization, retinal neovascularization, and ocular inflammation.
 130. The use of claim 128, wherein the eye disorder is aged-related macular degeneration (AMD).
 131. The use of claim 130, wherein the AMD is dry AMD.
 132. The use of claim 130, wherein the AMD is geographic atrophy.
 133. A method of making the binding agent of any one of claims 1-94 or the antibody of claim 95, comprising: (a) culturing the cell of any one of claim 102-104, and (b) isolating the binding agent or antibody.
 134. The method of claim 133, further comprising formulating the binding agent or antibody as a pharmaceutical composition. 